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I  I  V 


ADVERTISEMENT. 

[Monograph  XIII. J 


The  publications  of  the  United  States  Geological  Survey  are  issued  iu  accordance  with  the  statute 
approved  March  3,  1879,  which  declares  that — 

"The  publications  of  the  Geological  Survey  shall  consist  of  the  annual  report  of  operations,  geo- 
logical and  economic  maps  illustrating  the  resources  and  classification  of  the  lands,  and  reports  upon 
general  and  economic  geology  and  paleontology.  The  annual  report  of  operation.-!  of  the  Geological 
Survey  shall  accompany  the  annual  report  of  the  Secretary  of  the  Interior.  All  special  memoirs  and 
reports  of  said  Survey  shall  be  issued  in  uniform  c[U-ii'to  series  if  deemed  necessary  by  the  Director,  but 
otherwise  in  ordinary  octavos.  Three  thousand  copies  of  each  shall  bo  published  for  scientific  exchanges 
;iinl  for  sale  at  the  price  of  publication;  and  all  literary  and  cartographic  materials  received  iu  exchange 
shall  be  the  property  of  the  United  States  and  form  aipart  of  the  library  of  the  organization  :  And  th  • 
money  resulting  from  the  sale  of  such  publications  shall  be  covered  into  the  Treasury  of  the  Unite, I 
Slates." 

On  July  7,  188i,  the  following  joint,  resolution,  referring  to  all  Government  publications,  was 
passed  by  Congress: 

"That  whenever  any  document  or  report  shall  lie  ordered  printed  by  Congress,  there  shall  l>e 
printed,  inadditiou  to  the  number  in  each  case  stated,  the  'usual  number'  (1,900)  of  copies  for  binding 
iind  distribution  among  those  entitled  to  receive  them." 

Except  iu  those  cases»in  which  an  extra  number  of  any  publication  has  been  supplied  to  the  Sur 
vey  by  special  resolution  of  Cougress  or  has  been  ordered  by  the  Secretary  of  the  Interior,  this  oliice 
has  no  copies  for  gratuitous  distribution. 

ANNUAL  REPORTS. 

I.  First  Annual  Report  of  the  United  States  Geological  Survey,  by  Clarence  King.    1880.    »°.    7!) 
pp.    1  map. — A  preliminary  report  describing  plan  of  organization  and  publications. 

II.  Second  Annual  Report  of  the  United  States  Geological  Survey,  188Sf-'81,  by  J.  W.  Powell. 

1882.  8C.     Iv,  588  pp.    b'l  pi.     1  map. 

III.  Third  Annual  Report  of  the  United  Stales  Geological  Survey,  1881-'82,  by  J.  W.  Powell 

1883.  8°.     xviii,  5(>4  pp.     (i7  pi.  and  maps. 

IV.  Fourth  Annual  Report  of  the  United  States  Geological  Survey,  1882-'83,  by  J.  W.  Powell. 

1884.  8°.    xxxii,  471!  pp.    85  pi.  and  maps. 

V.  Fifth  Annual  Report  of  the  United  States  Geological  Survey,  1883-'84,  by  J.  W.  Powell. 
1385.     8°.     xxxvi,  4(51)  pp.     58  pi.  and  mans. 

VI.  Sixth  Annual  Report  of  the  United  States  Geological  Survey,  1884-'85,  by  J.  W.  Powell. 
l-'86.     8°.     xxix,  570  p[>.     <>5  pi.  and  maps. 

VII.  Seventh  Annual  Report  of  the  United  States  Geological  Survey,  1883-'8G,  by  J.  W.  Powell. 
1888.     8°.     xx,  65tj  pp.     ~2  pi.  and  maps. 

The  Eighth  and  Ninth  Annual  Reports  are  in  press. 

MONOGRAPHS. 

Monograph  I  is  not  yet,  published. 

II.  Tertiary  History  of  the  Grand  Canon  District,  with  atlas,  by  Clarence  E.  Duttoii,  Capt. ,  U.  S.  A. 
1882.     4°.     xiv,  264  pp.     42  pi.  and  atlas  of  24  sheets  folio.     Price  f  10.12. 

III.  Geology  of  the  Comstork  Lode,  and  the  Washoe  District,  with  atlas,  by  George  F.  Becker. 
1*-<2.     4°.     xv,  4*J  pp.     7  pi.  and  atlas  of  21  sheets  folio.     Price  $11. 

IV.  Comstock  Mining  and  Miners,  by  Kliot  Lord.     H83.     4°.     xiv,  451  pp.     3  pi.     Price  $1.51). 

V.  The  Copper-Hearing  Rocks  of  Lake,  Superior,  by  Roland  Duer  Irving.    1883.    4°.    xvi,  4ti4  pp. 
151.     29  pi.     Price  fl.8f>. 

VI.  Contributions  to  the-  Knowledge  of  the  Older  Meso/,oic  Flora  of  Virginia,  by  William  Morris 
Fontaine.     1883.     4°.     xi,  144  pp.     54  1.     54  pi.     Price  $1.05. 

VII.  Silver-Lead  Deposits  of  Eureka,  Nevada,  by  Joseph  Story  Curtis.     1881.     4°.     xiii,  200  pp. 
10  pi.     Price  |1. •,'(). 

VIII.  Paleontology  of  the  Eureka  District,  by  Churles  Doolittlo  Walcott.     18S1.     I  '.     xiii,2'.H  pp. 
241,    24  pi.     Price  $1.10. 

I 


I  [  ADVERTISEMENT. 


X.  Brachiopoda  and  La mcl I  i  branchial  a  of  the  Kan  tan  Clay  is  and  Oreonsaud  Marls  of  New  Jersey, 

>ert  P.  Whitiield.     1885.     4°.     xx,  338  pp.     3".  pi.     1  in;i]>.     Trice  SI. 15. 

C.  Dinocerata.     A  Monograph  of  :in  Extinct  Order  of  Gigantic  Mammals,  by  Othuiel  Charles 


IX 

by  Kobert 

X.  Dinocerata.     A  Monograj 

Marsh.     l->-(;.     4°.     xviii,  243pp.     561.     50  pi.    Price  $2.70. 

XI.  Geological  History  of  Lake  Lahontan,  a  Quaternary  Lake,  of  Northwestern  Nevada,  by  Israel 
Cook  Russell.     1S85.     4°.     xiv,  288  pp.     40  pi.  and  maps.     Price.  .*!. 75. 

XII.  Geology  and  Mining  Industry  of  Leadvillo,  Colorado,  with  atlas,  by  Samuel  franklin  Em- 
uions.     1S8G.     4°.     xxix,  770  pp.     45  pi.  and  atlas  of  35  sheets  folio.     Price  $>8.40. 

XIII.  Geologv  of  tht)  Quicksilver  Deposits  of  the'  Pacific  Slope,  with  atlas,  by  George  F.  Becker. 
1888.     4°.     xix,  486  pp.     7  pi.  and  atlas  of  14  sheets  folio.     Price  JJ2.00. 

XIV.  Fossil  Fishes  and  Fossil  Plants  of  the  Triassie  Rocks  of  New  Jersey  and  the  Connecticut 
Valley,  by  John  S.  Newberry.  .1888.     4°.     xiv,  152  pp.    26  pi.     Price  $1.00. 

In  preparation: 

XV.  Younger  Mesozoie  Flora  of  Virginia,  by  William  M.  Fontaine. 

XVI.  Paleozoic  Fishes  of  North  America,  by  J.  S.  Newbcrry. 

XVII.  Description  of  New  Fossil  Plants  from  the  Dakota  Group,  by  Leo  ].csi|iiereux. 
— Gasteropoda  of  the  New  Jersey  Cretaceous  and  Eocene  Marls,  by  K.  P.  Whitfield. 
— Geology  of  the  Eureka  Mining  District,  Nevada,  with  atlas,  by  Arnold  Hague. 

— Lake  Bonneville,  by  G.  K.  Gilbert. 

— Sanropoda,  by  O.  C.  Marsh. 

— Stegosauria,  by  O.  C.  Marsh. 

— Brontotheridto,  by  p.  C.  Marsh. 

— The  Penokee-Gogebic Iron- Bearing  Series  of  North  Wisconsin  and  Michigan,  by  Roland  D.  Irving. 

— Report  on  the  Denver  Coal  Basin,  by  S.  F.  Emmons. 

—Report  on  Silver  Clitf  and  Ten-Mile  Mining  District,  Colorado,  by  S.  F.  Einmous. 

— Flora  of  the  Dakota  Group,  by  J.  S.  Nowberry. 

— The  Glacial  Lake  Agassiz,  by  Warren  Uphani. 

— Geology  of  the  Potomac  Formation  in  Virginia,  by  W.  M.  Fontaine. 

BULLETINS. 

Each  of  the  Bulletins  contains  but  one  paper  and  is  complete  in  itself.  They  art1,  however,  num- 
bered iu  a  continuous  scries,  and  may  bo  bound  in  volumes  of  convenient  size.  To  facilitate  this,  each 
Bulletin  has  two  paginations,  one  proper  to  itself  and  another  which  belongs  to  it  as  part  of  I  be  volume. 

1.  On  Hyperstheno-Andesite  and  on  Triclinic  Pyroxene  in  Augitic  Rocks,  by  Whitman  Cross,  with 
a  Geological  Sketch  of  Buffalo  Peaks,  Colorado,  by  S.  F.  Euimons.    1883.    81-'.    42pp.    2  pi.     Price  in 
cents. 

2.  Gold  and  Silver  Conversion  Tables,  giving  the  coining  values  of  troy  ounces  of  line  metal,  etc., 
computed,  by  Albert  Williams,  jr.     1883.     8°.    8pp.    Price  5  cents. 

3.  On  the  Fossil  Faunas  of  the  Upper  Devonian  along  the  meridian  of  7(i "30',  from  Tompkins 
County,  N.  Y.,  to  Bradford  County,  Pa.,  by  Henry  S.  Williams.     1884.     8°.     3G  pp.    Price  5  cents. 

4.  On  Mesozoic  Fossils,  by  Charles  A.  White.     1884.     8°.     36  pp.     Dpi.     Price  f>  ccnls. 

5.  A  Dictionary  of  Altitudes  in  the  United  States,  compiled  by  Henry  Gannett.    1884.    8''.    325pp. 
Price  20  cents. 

6.  Elevations  in  the  Dominion  of  Canada,  by  J.  VV.  Spencer.     1884.     8°.     43  pp.     Price  5  cents. 

7.  Mapotcca  Geologica  Americana.    A  Catalogue  of  Geological  Maps  of  America  (North  and  South), 
17f>2-1881,  in  geographic  and  chronologic  order,  by  Jules  Marcou  and  John  Belkuap  Marcou.     1884. 
8°.     184  pp.     Price  10  cents. 

8.  On  Secondary  Enlargements  of  Mineral  Fragments  in  Certain  Rocks,  by  R.  D.  Irving  and  C.  R. 
Van  Hise.     1884.    8°.     56  pp.  6  pi.     Price  10  cents. 

9.  A  Report  of  work  done  in  the  Washington  Laboratory  dnrmg  the  liscal  year  1883-'84.     F.  W. 
Clarke,  chief  chemist;  T.  M.  Chatard,  assistant  chemist.     1884.     8°.     40pp.     Price  5  cents. 

111.  On  the  Cambrian  Faunas  of  North  America.  Preliminary  studies,  by  Charles  Doolittle  Wal- 
cott.  1884.  8°.  74, pp.  10  pi.  Price  5  cents. 

11.  On  the  Quaternary  and  Recent  Mollusca  of  the  Great  Basin  ;   with  Descriptions  of  New  Forms, 
b\  M.  Ellsworth  Call.-   Introduced  by  a  sketch  of  the  Quaternary  Lakes  of  the  Great  Basin,  bv  G.  K. 
Gilbert.     1881.     8°.     Gli  pp.     6  pi.     Price  5  cents. 

12.  A  Cr.vstallographic  Study  of  the  Thijiolite  »f  Lake  Lahontan,  by  Edward  S.  Duna.     1884.     8°. 
31  pp.     3  pi.     Price  5  cents. 

13.  Boundaries  of  the  United   States  and  of  the  several  Slates  and  Territories,  with  a  Historical 
Sketch  of  the  Territorial  Changes,  by  Henry  Gannett.      IS-C>.     H '.     135  pp.     Price  10  cents. 

14.  The,  Electrical  and  Magnetic  Properties  of  the  Iron-Carburets,  by  Carl  Barns  and  Vincent 
Slronhal.     1885.     tf°.     238pp.     Price  15  cents. 

!.">.  On  the  SJeMi/oic  and  CYnozoic  Paleontology  of  California,  by  Charles  A.  White.  1885.  8°. 
33  pp.  Price  5  cents. 

Hi.  On  the  Higher  Devonian  Faunas  of  Ontario  County,  New  York,  by  John  M.  Clarke.  1885.  8~. 
,-li  pp.  :<  pi.  Price  :">  cents. 

17.  On  the  Development  of  Cr.x slalli/.al  ion  in  the  Igneous  Rocks  of  Washoe,  Nevada,  with  Notes 
on  the  Geology  of  (lie  District,  by  Arnold  Hague  and  Joseph  P.  Iddings.  18*5.  8°.  44  pp.  Price  5 
cents. 


ADVERTISEMENT.  Ill 

18.  On  Marine  Eocene,  Fresh-water  Miocene,  and  other  Fossil  Molhisca  of  Western  North  America, 
by  Charles  A.  White.     1885.     8°.     20pp.     3  pi.     Price  5  cents. 

19.  Notes  on  the  Stratigraphy  of  California,  by  GeorgoF.  Becker.    1885.    8°.    28pp.    Price5cents. 

20.  Contributions  to  too  Mineralogy  oC  tint  Rooky  Mountains,  !>y  Wliitman  Cross  and  W.  F.  Hi  lie- 
brand.     H85.     8°.     114  pi>.     1  pi.     Price' 10  cents. 

21.  The  Lignites  <>t  'the  (treat  Sioux  Reservation.     A  Report  on  the  Region  hot.  ween  the  Grand  and 
Morean  Rivera,  Dakota,  by  Bailey  Willis.     188.').    8°.     1C  pp.    ,r>pl.    Priee  5  rents. 

2-1.  On  New  Cretaceous  Fossils  from  California,  liy  Charles  A.  White.  13S5.  8°.  35pp.  5  pi. 
Price  r>  ceuts. 

23.  Observations  on  the  .Junction  bstween  the  Eastern  Sandstone  and  the  Kewet,naw  Sjries  oa 
Keweeuaw  Point,  Lake  Superior,  by  11.  D.  Irving  and  T.  C.  Chamberlin.     18ir>.     8°.     121  pp.     17  pi. 
Price  l.'i  cents. 

24.  List  of  Marino  Mollnsca,  comprising  the  Quaternary  fossils  and  recent  forms  from  American 
Localities  between  Cape  HaUeras  and  Capo  Roqne,  including  the  Bermudas,  by  William  llealey  Dall. 
1*35.     8°.     :i:!G  pp.     Price  25  cents. 

25.  The  Present  Technical  Condition  of  the  Steel  Industry  of  the  United  States,  liv  Phineas  Barnos. 
1835.     8°.    85  pp.     1'rico  10  cents. 

20.  Copper  Smelting,  by  Henry  M.  Howe.    1885.     8°.     107pp.     Price  10  cents. 

27.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1884-'85.     1886.     8°.     80  pp.    Price  10  cents. 

28.  The  Gabbros  and  Associated  Hornblende  Rocks  occurring  in  the  Neighborhood  of  Baltimore, 
Md.,  by  George  lluntington  Williams.     1886.     8°.     78pp.    4  pi.     Price  10  cents. 

29.  On  the  Fresh-water  In  vertebrates  of  the  North  American  Jurassic,  by  Charles  A.  White.    183.5. 
8°.     41  pp.    4  pi.     Price  5  cents. 

30.  Second  Contribution  to  the  Studies  on  the  Cambrian  Faunas  of  North  America,  by  Charles 
Doolittle  Walcott.     1*80.    8e.     309  pp.     3:5  pi.     Price  25  cents. 

31.  Systematic  Review  of  our  Present  Knowledge  of  Fossil  Insects,  including  Myriapods  and 
Arachnids,  by  Samuel  llnbbard  Scudder.     1830.     8°.     128  pp.     Price  15  cents. 

32.  Lists  and  Analyses  of  the  Mineral  Springs  of  the  United  States;  a  Preliminary  Study,  bv 
Albert  C.  Pealo.     1880.     8°.     235pp.     Price  20  cents. 

33.  Notes  on  the  Geology  of  Northern  California,  by  J.S.Dillor.     1830.     8°.    23pp.    Price  5  cents. 

34.  On  the  relation  of  the  Laramie  Molluscan  Fauna  to  that  of  the  succeed  ing  Fresh- water  Eocene 
and  other  groups,  by  Charles  A.  White.     188U.     8°.     54pp.     5  pi.     Price  10  cents. 

:!f>.  Physical  Properties  of  the  Iron-Carburets,  by  Carl  Barns  and  Vincent  Stronhal.  1883.  8°. 
Gv!  pp.  Price  10  cents. 

36.  SiibsidenceofFiueSolidParticlesiiiLiquiils,  byCarl  Barus.    188>i.    8°.    58pp.    Price  lOceuts. 

37.  Types  of  the  Laramie  Flora,  by  Lester  F.  Ward.     1887.    8J.     354pp.     57  pi.     Price  25  ceuts. 
3*.  Peridoti  to  of  Elliott  County,  Kentucky,  by.  I.  S.  Diller.    1887.    8°.    31pp.    1  pi.    Price  5  cents. 
31).  The  Upper  Beaches  and  Deltas  of  the  Glacial  Lake  Agassiz,  by  Warren  Upham.     1887.     8°. 

84  pp.     1  pi.     Price  10  cents. 

40.  Changes  in  River  Courses  in  Washington  Territory  duo  to  Glaciation,  by  Bailey  Willis.    1837. 
8°.     10pp.     4  pi.     Price  5  cents. 

41.  On  the  Fossil  Faunas  of  the  Upper  Devonian — the  Gonesee  Section,  New  York,  by  Henry  S. 
Williams.     18*7.     8°.     121  np.     4  pi.     Price  15  cents. 

42.  Report  of  work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1—  .V80.     F.  W.  Clarke,  chief  chemist.     1887.     8°.     152pp.     1  pi.'  'Price  15  cents. 

4:!.  Tertiary  and  Cretaceous  Strata  of  the  Tnscaloosa,  Tomhigbeo,  and  Alabama  Rivers,  by  Eugene 
A.  Smith  and  Lawrence  C.  Johnson.  1*37.  8°.  180  pp.  21  pi.  Price  15  cents. 

44.  Bibliography  of  North  American  Geology  for  183!'),  by  Nelson  II.  Darton.     1887.     8°.     35  pp. 
Price  5  cents. 

45.  The  Present  Condition  of  Knowledge  of  the  Geology  of  Texas,  by  Robert  T.  Hill.     1887.     8°. 
94  pp.     Price  10  cents. 

46.  Nature  and  Origin  of  Deposits  of  Phosphate  of  Lime,  by  R.  A.  F.  Ponrose,  jr.,  with  an  Intro- 
duction by  N.  S.  Slialcr.     1*83.     8°.     143  pp.     Price  15  ceuts. 

47.  Analyses  of  Waters  of  the  Yellowstone  National  Park,  with  an  Account  of  the  Methodiof 
Analysis  employed,  by  Frank  Austin  Gooch  and  James  Edward  Whit  lield.     1338.     8°.     84pp.     Price 
10  cents. 

48.  On  the  Form  and  Position  of  the  Sea  Level,  by  Robert  Simpson  Woodward.     1833.     8°.     88 
pp.     Price  ID  cents. 

Numbers  1  to  ('<  of  the  Bulletins  form  Volume  I;  Numbers  7  to  14,  Volume  II;  Numbers  15  to  23, 
Volume  III;  Numbers  24  to  30,  Volume  IV;  Numbers  3L  to  :!;!,  Volume  V:  Numbers  :17  to  41,  Volume 
VI;  Numbers  42  to  40,  Volume  VII.  Volume  VIII  is  not  yet  complete. 

In  press: 

49.  On  the1  Latitudes  ami  Longitudes  of  Certain  Points  in  Missouri,  Kansas,  and  New  Mexico,  by 
R.  S.  Woodward. 

50.  Formulas  and  Tables  to  facilitate  the  construction  and  use  of  Maps,  by  R.  S.  Woodward. 

51.  Invertebrate  Fossils  from  California,  Oregon,  Washington  Territory,  and  Alaska,  by  C.  A. 
White. 

52.  On  the  Snbaerial  Decay  of  Rocks  and  the  Origin  of  the  Red  Color  of  Certain  Formations,  by 
Israel  C.  Russell. 

53.  Geology  of  the  Island  of  Nantncket,  by  N.  S.  Shaler. 


IV  ADVERTISEMENT. 

In  preparation : 

—  Notes  on  the  Geology  of  Southwestern  Kansas,  by  Robert  Hay. 

—  On  the  Glacial  Boundary,  by  G.  F.  Wright. 

—  The  Gabbros  and  Associated  Rocks  in  Delaware,  by  F.  D.  Chester. 

—  Fossil  Woods  and  Lignites  of  the  Potomac  Formation,  by  F.  H.  Kno\vltou. 

—  Mineralogy  of  the  Pacific  Coast,  by  W.  II.  Melville  and  Waldera&r  Lindgreu. 

—  Report  of  work  done  iu  the  Division  of  Chemistry  and  Physics,  mainly  during  the  fiscal  year 
1836-'87. 

—  A  Report  on  the  Thermo  Electrical  Measurement  an  1  High  Temperatures,  by  Carl  Barns. 

—  The  Greenstone  Schist,  Areas  of  the  Mcnoininee  an;l  .\I.in|iii'tti'  R  'gions  of  Michigan,  by  George 
H.  Williams;  with  an  introduction  by  R.  D.  Irving. 

—  Bibliography  of  the  Paleozoic  Crustacea,  by  A.  W.  Vogdes. 

—  The  Viscosity  of  Solids,  by  Carl  Barns. 

—  Author-Catalogue  of  Contributions  to  North  American  ({oology,  by  N.  II.  Darton. 

—  On  a  Group  of  Volcanic  Rocks  from  thoTewan  Mountains,  New  Mexico,  and  on  the  occurrence 
of  Primary  Quartz  in  certain  Basalts,  by  J.  P.  Iddings. 

—  On  the  relation-!  of  Ihe  Traps  of  the  Jura-Trias  of  New  Jersey,  bv  N.  H.  Darton. 

—  Altitudes  between  Lake  Superior  and  the  Rocky  Mountains,  by  Warren  Upham. 

—  Mesoxoic  Fossils  in  the  Permian  of  Texas,  by  C.  A.  White. 

STATISTICAL  PAPERS. 

Mineral  Resourcei  of  the  United  States  [1832],  by  Albert  Williams,  jr.  188:?.  8°.  xvii,  813  pp. 
Price  r>0  cents. 

Mineral  Resources  of  the  United  States,  1333  ami  1834,  by  Albert  Williams,  jr.  1885.  8°.  xiv, 
lolii  pp.  Price  <>0  cents. 

Mineral  Resources  of  the  United  States,  1835.  Division  of  Mining  Statistics  and  Technology. 
l*8.i.  8J.  vii,  r.7i>  pp.  Price  40  cents. 

Mineral  Resource!  of  the  Unite:!  States,  183.5,  by  D.ivid  T.  Diy.     1337.     8°.     viii,  81.!  pp.     Pri.-o  ' 
50  cents. 

Mineral  Resources  of  the  United  States,  1837,  by  David  T.  Day.  1833.  8°.  vii,  832  pp.  Price 
f>0  cents. 

In  preparation : 

Mineral  Resources  of  the  United  States,  1888,  by  David  T.  Day. 

The  money  received  from  the  sale  of  these  publications  is  deposited  in  the  Treasury,  and  tin- 
Secretary  of  that  Department  declines  to  receive  bank  checks,  drafts,  or  postage  stamps ;  all  remit- 
tances, therefore,  must  be  by  POSTAL  NOTE  or  MONEY  ORDER,  made  payable  to  the  Librarian  of  the 
U.  S.  Geological  Survey,  or  in  CURRENCY  for  the  exact  amount.  Correspondence  relating  to  the  pub- 
lications of  the  Survey  should  be  addressed 

To  THE  DIRECTOR  OF  THE 

UNITED  STATES  GEOLOGICAL  SURVEY, 

WASHINGTON,  D.  C. 
WASHINGTON,  D.  C.,  March  15,  1889. 


ADVERTISEMENT. 


LIBRARY  CATALOGUE  SLIPS. 

United  States.     Ilcpartmmt  of  the  interior.     (  U.  S.  geological  survey). 

Department  of  the  interior  |  —  |  Monographs  |  of  the  |  United 
States  geological  survey  |  Volnmo  XIII  |  [Seal  of  the  tlepart- 
inent]  | 

Washington  |  government  printing  office  |  1888 

Second    till,':    United   States  geological   survey  |  J.   W.  Powell, 

director  |  —  |  Geology  |  of  the  |  quicksilver  deposits  |  of  the  |  Pa- 

'  cilic   slope  |  with   an  atlas  |  liy  |  George  F.   Becker  |  [Vignette]  | 

Washington  |  governme,  it  printing  office  |  1888 

4°.     six,  480  pp.  7  )il.  am\  folio  atlas  of  14  pi. 


Becker  (George  Ferdinand). 

United  Srat.es  geological  survey  |  J.  W.  Powell,  director  |  —  | 
Geology  !  ofthe  !  (juioksilverdeposita  |  of  the  |  Pacific  slope  |  with 

an  atlas  |  l,y  |  George  F.  Becker  |  [Vignette]  | 
Washinglon  |  government  printing  office  |  1888 
4°.    six,  48(5  pp.  7  pi.  anil  fi.lio  atlas  of  14  pi. 
[UsiTF.i>  STATUS.     Department  of  the  interior.     (U.  S.  geological   eurvey) 

Monograph   XIII|. 


United  States  geological    survey  |  J.    \V.  Powell,  director  |  —  | 
.  Geology  |  ofthe  |  qnickgilverdepoaita  |  of  the  |  Pacific  slope  |  with 

K,  an  atlas  |  l.y  |  (J.-orge  F.   Bec.ker  |  [Vignette]  | 

Washinijton  |  goveruinent.  printing  office  |  18S8 
J|  40.     xi\-,  4xii|,p.  7  pi.  anil  folio  atlas  of  14  pi. 

(UNITED  STATUS.     Department   of  the  interior.     (U.  S.  geological 
Monograph  XIII]. 


UFI7BESITT 


U.  S.  GEOLOGICAL    SURVEY 


MONOGRAPH   XHI,  PL.  1. 


SKETCHMAP   SHOWING 

DISTRIBUTION  OF  QUICKSILVER  MINES 
IN  CALIFORNIA 


friucipal  Surveys          •  Other  deposits  referred  to 
Minor  Surveys  .  o    Traces  oi'ore 


SteamboaT  Spring 


124°  123' 


f  n-ii  I'  Becker, Geolo^isl  in  charge. 


UNITED  STATES  GEOLOGICAL  SURVEY 

J.  W.   POWELL,  IIRECTOR 


GEOLOGY 


OK   THE 


QUICKSILVER    DEPOSITS 


OF   THE 


PACIFIC    SLOPE 


WITH   AN  ATLAS 


BY 


UNIVERSITY 


GEORGB   T.   BECKER 

\\ 


WASHINGTON 
GOVERNMENT    PRINTING    OFFICE 

1888 


LETTER  OE  TRANSMITTAL 


DEPARTMENT  OP  THE  INTERIOR, 

U.  S.  GEOLOGICAL  SURVEY, 
CALIFORNIA  DIVISION  OF  GEOLOGY, 

Washington,  D.  C.,  July  19,  1887. 

•./ 

SIR:  I  have  the  honor  to  transmit  herewith  a  report  on  the  geology  of 
the  quicksilver  deposits  of  the  Pacific  slope,  prepared  in  accordance  with 
your  instructions. 

Very  respectfully,  your  obedient  servant, 

GEORGE  F.  BECKER, 

Geologist  -in  Charge. 
Hon.  J.  W.  POWELL, 

Director  U.  S.  Geological  Survey. 


'   OT  THR        ^ 

[TJHIVZRSITY) 


CONTENTS. 


Page. 

LETTER  OKTUAXSMITTAI, v 

PREFACE- xm 

111: IKK  OUTLINE  OK  KESl'I.TS XV 

CHAPTER  I.  Statistics  and  history 1 

II.  Notes  on  foreign  occurrences  of  quicksilver 14 

III.  The  sedimentary  rocks 56 

IV.  The  massive  rocks 140 

V.  Struc'.  ural  and  historical  geology  of  tbe  quicksilver  belt 176 

(Appendix  to  Chapter  V,  remarks  on  the  genus  Aucella,  by  Dr.  C.  A.  White) 226 

VI.  Descriptive  geology  of  the  Clear  Lake  region 233 

VII.  Descriptive  geology  of  Sulphur  Bank 251 

VIII.  Descriptive  geology  of  the  Knoxville  district 271 

IX.  Descriptive  geology  of  the  New  Idria  district 291 

X.  Descriptive  geology  of  the  New  Almadou  district 310 

XI.  Descriptive  geology  of  the  Steamboat  Springs  district 331 

XII.  Descriptive  geology  of  the  Oathill,  Great  Western,  and  Great  Eastern  districts 354 

XIII.  Other  deposits  of  the  Pacific  slope 365 

XIV,  Discussion  of  the  ore  deposits 387 

XV.  On  the  solution  and  precipitation  of  cinnabar  and  other  ores 419 

XVI.  The  origin  of  the  ore 438 

XVII.  Summary  of  results 451 

INDEX , .". 477 

VII 


ILLUSTRATIONS. 


Page. 

PLATE  I.  Distribution  of  quicksilver  mines  in  California Frontispiece 

II.  Distribution  of  quicksilver  deposits  throughout  the  world 15 

III.  European  and  other  foreign  forms  of  Aucella   231 

IV.  American  forms  of  ducella 232 

V.  Geological  map  of  Oathill 354 

VI.  Geological  map  of  the  Great  Western  district 358 

VII.  Map  of  the  Great  Eastern  district 362 

Fio.    1.  Zoisite  microlites 78 

2.  Authigenetic  augite  in  altered  sandstone 88 

3.  Authigenetic  hornblende  in  altered  sandstone 89 

4.  Clastic  quartz  partially  converted  to  serpentine 123 

5.  Ruptures  produced  by  compression  of  strata 236 

6.  Dendritic  sinter  on  the  shore  of  Borax  Lake 206 

7.  Partly  metamorphosed  anticlinal 276 

8.  Sandstone  undergoing  serpentinization 277 

9.  Serpentine  forming  from  sandstone 278 

10.  Diagrammatic  vertical  cross-section  of  the  Reding  ton  mine 289 

11.  Contact  between  metamorphic  rocks  and  Chico  beds 296 

12.  Sketch  of  New  Idria  ore  bodies 303 

13.  Fissures  of  the  New  Alniaden  district 329 

14.  Vertical  cross-section  of  the  Napa  Consolidated  mine 357 

15.  Vertical  cross  section  of  the  Great  Western  mine 360 

16.  Vertical  longitudinal  section  of  the  Great  Western  mine 361 

17.  Vertical  cross-section  of  the  Great  Eastern  mine 364 

18.  Geological  sketch  map  of  the  Mayacmas  Range 369 

19.  Linked  veins , 410 

20.  Simple  fissure  vein  and  chambered  vein 411 

IX 


LIST  OF  ATLAS   SHEETS. 


SHKKT    I.    Title. 

II.    Contents. 

III.  Geological  map  of  the  Clear  Lake  district. 

IV.  (Zoological  map  of  the  Sulphur  Bank  district. 

<  Topographical  map  of  the  region  of  Clear  Lake. 
(  Geological  map  of  the  Kuoxville  district. 
VI.     Geological  map  of  the  New  Idria  district. 
VII.     Geological  map  of  the  New  Almadeu  district. 
VIII.     Ore  bodies  of  the  New  Almaden  shown  beneath  the  topography. 
IX.     Map  of  the  workings  of  the  New-  Almaden  mine. 

X.     Vertical  cross-section  of  the  New  Almaden  mine  on  a  broken  line  nearly  north  and  south. 
XI.     Two  north  and  south  sections  of  the  New  Almadeu  mine. 
XII.     Kast  and  west  section  of  the  New  Almaden  mine. 

XIII.  Plan  of  clays,  New  Almaden  mine. 

XIV.  Geological  map  of  the  Steamboat  Springs  district. 

XI 


TJFIVE1         7 


PREFACE. 


The  field  work  of  the  investigations  recorded  in  this  volume  occupied 
nearly  the  whole  of  three  seasons,  beginning'  in  1883.  •  All  the  mines  might 
have  been  examined  and  the  maps  colored  in  a  much  shorter  time,  but  it 
was  found  soon  after  the  examinations  were  begun  that  they  could  not  be 
completed  satisfactorily  without  also  solving  some  important  general  prob- 
lems affecting  the  whole  region,  and  much  of  the  time  spent  was  devoted 
to  these  questions. 

The  examinations  of  the  Knoxville  and  New  Idria  districts  furnished 
me  with  strong  paleontological  and  structural  grounds  for  believing  that 
an  important  and  previously  undetermined  non-conformity  existed  in  the 
Coast  Ranges.  On  my  application,  Dr.  C.  A.  White  devoted  one  season  to 
examining  my  collections  of  fossils  and  their  field  occurrence  with  me.  He 
indorsed  my  conclusions  in  all  respects.  The  paleontological  statements 
of  this  report  are  all  on  his  authority,  excepting  where  otherwise  accredited. 

It  was  found  that  the  quicksilver  districts  of  California  afforded  a  re- 
markable opportunity  for  the  investigation  of  the  metamorphism  of  Meso- 
zoic  rocks  and  that  it  was  highly  desirable  to  determine  what  connection,  if 
any,  existed  between  the  formation  of  ore  deposits  and  this  metamorphism. 
The  investigation  occupied  much  time  and  was  most  laborious. 

It  was  known  before  these  investigations  were  undertaken  that  the 
deposition  of  cinnabar  was  probably  still  taking  place  at  Sulphur  Bank  and 
Steamboat  Springs.  It  was  of  course  necessary  to  make  an  effort  to  dis- 
cover whether  such  was  really  the  case,  and,  if  so,  under  what  conditions 
the  solution  and  precipitation  of  cinnabar  and  the  accompanying  minerals 
occurred.  The  problems  presented  by  this  inquiry  were  far  from  being 
simple  or  readily  solved. 

Dr.  W.  H.  Melville  has  had  charge  of  my  laboratory  throughout  the 
period  covered  by  these  investigations.  He  has  made  all  the  analyses  re- 


XIII 


xiv  PREFACE. 

corded  in  this  report,  as  well  as  a  large  part  of  the  experiments.  A  portion 
of  his  time  has  been  occupied  in  investigations  which  are  not  recorded  here, 
but  which  I  hope  to  publish  soon.  His  work  has  been  very  difficult,  but 
entirely  satisfactory  to  me. 

Mr.  H.  W.  Turner  has  assisted  me  in  all  the  field  work,  and  Chapter 
XII  is  written  from  his  notes.  His  accuracy  and  powers  of  observation  have 
been  very  valuable  to  me.  Mr.  Waldemar  Lindgren  joined  me  only  in  time 
for  the  last  season's  field  work.  His  assistance  in  the  microscopical  lithology 
has  been  very  efficient  and  important.  I  could  not  without  aid  have  accom- 
plished in  a  reasonable  time  so  trying  an  investigation  as  that  of  the  meta- 
morphic  rocks  of  the  Coast  Ranges. 

For  myself,  I  may  say  that  I  have  studied  with  care  in  the  field 
every  portion  of  the  areas  surveyed  in  detail ;  I  spent  months  at  the  micro- 
scope and  made  many  important  chemical  experiments  on  the  solubility  of 
ores.  It  has  been  my  endeavor  to  do  justice  to  all  sides  of  a  very  fine  sub- 
ject and  to  draw  only  legitimate  conclusions  from  the  facts  observed  by  my 
assistants  and  myself.  I  approached  the  problems  mentioned  above  entirely 
without  preconceived  ideas  of  the  solutions  to  be  reached,  and  have  expressed 
my  conclusions  as  to  the  geology  of  California  or  of  other  regions  without 
regard  to  the  opinions  of  others;  but,  while  entertaining  some  confidence  in 
the  correctness  of  my  results  for  the  region  surveyed,  I  do  not  even  incline 
to  the  hypothesis  that  all  crystalline  sedimentary  rocks  have  a  history  similar 
to  that  of  those  which  I  have  described  or  that  ore  deposits  are  all  formed  in 
a  similar  way. 

» 

The  superintendents  of  the  mines  examined  have  afforded  me  every 
facility,  often  at  inconvenience  to  themselves,  and  I  have  much  to  thank 
them  for.  Mr.  Louis  Janin  has  supplied  me  with  many  valuable  notes 
gathered  in  his  large  experience  as  a  mining  expert.  Mr.  Frank  Reade,  who 
assisted  me  in  examining  the  Comstock  lode,  was  surveyor  of  the  New 
Almaden  mine  during  the  period  covered  by  the  present  investigation,  and 
he  prepared  for  me  the  excellent  plans  and  sections  of  that  mine. 

In  addition  to  those  who  took  part  in  the  present  investigation  I  am 
indebted  to  numerous  previous  observers,  to  whom  I  have  endeavored  to 
assign  due  credit  in  the  proper  places. 


PREFACE.  xv 

Readers  will  perhaps  notice  the  absence  of  illustrations  of  magnified 
thin  sections  in  this  volume.  After  having  presented  in  a  former  report 
illustrations  of  tins  kind  which  are  generally  acknowledged  to  be  unsur- 
passed by  any  yet  published,  I  have  come  to  the  conclusion  that  the  lessons 
which  they  teach  do  not  repay  their  cost  in  time  and  money. 

I  have  thought  it  best  to  make  each  chapter  in  this  volume  as  far  as 
possible  independent  of  the  rest.  In  doing  so  I  am  sure  that  I  meet  the 
wishes  of  many  readers  who  will  care  to  consult  only  certain  portions  of 
the  book.  This  plan,  however,  involves  some  repetition,  which  may  prove 
wearisome  to  continuous  readers.  I  crave  their  indulgence  in  this  resped; 
for  the  sake  of  the  larger  class.  Personally,  I  should  prefer  never  to  re- 
state a  fact  or  an  opinion. 

After  the  manuscript  of  this  report  was  substantially  completed  I  was 
authorized  to  visit  the  great  Almaden  mine  in  Spain  and  the  Tuscan  deposits. 
Such  a  visit  was  almost  essential  to  the  purposes  of  the  investigation ;  for  the 
results  which  I  had  reached  from  study  of  the  American  deposits  differed  in 
important  respects  from  the  conclusions  of  some  geologists  respecting  the 
great  Spanish  deposit  If  they  were  right,  it  became  necessary  to  warn 
American  miners  that  cinnabar  might  be  looked  for  under  very  different 
conditions  from  those  described  in  this  volume.  If  the  greatest  quicksilver 
deposit  of  the  world  proved  similar  in  its  mode  of  occurrence  to  those  of 
California,  the  conclusions  drawn  from  the  latter  would '  gain  greatly  in 
strength.  I  had  the  satisfaction  of  finding  that  the  deposit  of  Almaden 
showed  an  association  with  eruptive  phenomena,  a  structure,  and  a  mineral 
association  similar  to  those  which  are  typical  of  the  Pacific  slope.  Such 
statements  as  that  the  Almaden  ore  bodies  are  not  veins-,  that  the  cinnabar 
is  free  from  other  sulphides,  that  it  is  accompanied  by  no  gangue  minerals, 
that  it  was  deposited  with  the  inclosing  rocks,  that  it  is  deposited  by  sub- 
stitution for  sandstone,  and  that  there  is  no  evidence  of  a  connection  between 
the  deposition  and  eruptive  phenomena — these  allegations  are,  in  my  judg- 
ment, erroneous.  The  Tuscan  deposits,  too,  I  found  similar  to  some  in  Cali- 
fornia. Only  a  few  notes  concerning  my  studies  of  these  mines  are  included 
in  this  volume.  I  exuect  to  write  more  fully  of  them  hereafter. 

JULY,  1887. 


BRIEF  OUTLINE  OF  RESULTS. 

Quicksilver  appears  to  be  rather  more  than  three  times  as  abundant  in  nature  as  silver.  The 
quicksilver  produced  in  the  world  from  1850  to  1885,  inclusive,  weighed  1.74  times  as  much  as  the  silver 
produced,  but  the  value  of  the  silver  \vas  about  1G.4  times  that  of  the  quicksilver.  The  great  quick- 
silver-producing localities  of 'the  world  have  been  Almaden  in  Spain,  Idi'ia  in  Austria,  Huancavelica 
in  Peru,  California,  and  the  province  of  Kwei-Chau  in  China.  No  statistics  are  known  to  exist  of  the 
Chinese  product.  The  total  known  products  of  the  other  regions  take  rank  in  the  order  in  which  they 
are  named  above,  but  of  late  years  Peru  has  produced  uothiug  and  from  1850  to  1885  California  yielded 
about  half  the  total  product.  The  production  of  Italy  is  more  important  than  it  is  usually  assumed 
to  be.  In  1886  the  yield  was  7,478  flasks.  The  production  of  California,  which  was  nearly  80,000 
flasks  in  1677,  was  only  about  30,000  in  1886. 

A  chain  of  quicksilver  deposits  of  very  greatly  varying  commercial  importance  almost  girdles  the 
world.  Beginning  in  Spain,  these  deposits  are  distributed  along  the  great  chain,  including  the  Alps, 
Caucasus,  and  Himalayas  to  China  ;  thence  through  Japan  along  the  eastern  edge  of  the  Asiatic  conti- 
nent to  the  Arctic  circle,  Beginning  again  in  Alaska,  the  deposits  follow  the  western  Cordilleras  down 
to  Chili.  Brief  descriptions  of  the  more  important  or  more  interesting  of  these  deposits  are  given  in 
Chapter  II  and  serve  as  an  introduction  to  the  discussions  of  the  deposits  of  the  Pacific  slope. 

The  sedimentary  rocks  of  the  Coast  Ranges  of  California  are  almost  all  composed  of  granitic 
detritus.  A  portion  of  those  havo  been  subjected  to  very  intense  metamorphisin  and  have  been  con- 
verted into  thoroughly  crystalline  rocks,  in  part  schistose.  These  rocks  are  of  Cretaceous  age  and  are 
grouped  as  pseudodiabasc,  pseudodiorite,  glaucophane-schists,  phthanites,  and  serpentine.  Very 
elaborate  field  studios,  microscopical  examinations,  and  chemical  analyses  of  these  rocks  are  given  in 
Chapter  III,  which  is  mainly  devoted  to  the  investigation  of  their  origin  and  the  processes  by  which 
they  have  become  reerystalline.  The  conclusion  reached  is  that  dynamical  action,  together  with 
warm  waters  carrying  imigncsian  salts  and  silica  in  solution,  effected  the  metamorphi?  a  at  the  epoch 
of  an  exceedingly  violent  upheaval.  This  chapter  also  includes  an  investigation  of  concretions  in 
sandstone,  which  are  referred  to  the  action  of  organic  matter,  and  an  analysis  of  the  conditions  under 
which  decomposition  xvill  produce  rounded  nodules,  like  pebbles. 

The  massive  rocks  of  the  quicksilver  areas  include  granite,  ancient  porphyries,  andesites,  rhyolite, 
and  basalt,  A  new  group  of  andesites  is  discussed,  for  which  the  name  anperites  is  suggested.  It  is 
shown  that  these  rocks  are  of  variable  mi neralogical  composition,  even  in  the  same  eruptions,  while 
all  of  I  hem  share  a  trachytic  habitus.  The  name,  is  simply  a  latinized  equivalent  of  trachyte.  Very 
remarkable  andcsitic  and  basaltic  glasses  occur  near  Clear  Lake  in  areas  of  unusual  size.  These 
glasses  are  extremely  aeid,  but  rontain  als>.  -i  very  high  percentage  of  alkalis,  and  it  is  because  of  this 
peculiar  chemical  composition  (hat  they  have  failed  to  crystallize,  not  because  they  have  cooled  more 
rapidly  or  under  less  pressure  than  the  accompanying  crystalline  rocks.  An  attempt  is  also  made  to 
show  that  the  original  crust  of  the  earth  was  granitic  and  reasons  are  given  for  believing  that  the 
MON  XIII II  XVII 


xvni  BRIEF  OUTLINE  OF  RESULTS. 

primeval  rock  is  exposed  in  California.    The  lavas  burst  through  the  granite,  and  the  conclusion  is 
reached  that  they  cannot  possibly  consist  of  reinelted  sediments. 

The  historical  and  structural  geology  of  the  quicksilver  belt  is  discussed  in  Chapter  V.  It  is 
shown  that  the  metamorphosed  rocks  pass  over  into  early  Crctaoeous  beds  containing  a  very  charac- 
teristic fossil  of  the  genus  Aucclla.  Soon  after  the  era  in  which  this  mollusk  lived  —  the  Neornmian  — 
occurred  the  great  upheaval  which  induced  the  metamorphism.  The  next  strata  in  point  of  ago  com- 
prise a  hitherto  undetected  group  of  the  middle  Cretaceous  called  the  Wallala  beds.  They  were  laid 
down  uncouformably  on  the  already  metamorphosed  Neocomian.  At  the  very  end  of  the  Cretaceous 
the  Chico  series  were  deposited  for  the  most  part  on  the  metamorphic  rocks  and  unconformably  with 
them.  Following  the  Chico  are  the  Tejon  beds,  which  are  here  regarded  as  Eocene;  but  there  was 
continuity  of  life  and  of  sedimentation  from  the  Chico  to  rheTeJon,  or  fiom  the  Cretaceous  to  the  Ter- 
tiary—  a  state  of  things  detected  nowhere  else  in  the  northern  hemisphere.  Upou  the  T^jou  lie  the 
Miocene  rocks  with  no  notable  non-conformity.  The  close  of  the  Miocene  was  marked  by  an  impor- 
tant upheaval,  which  was  recognized  by  earlier  observers.  The  volcanic  period  seems  to  have  begun 
nearly  at  this  time.  The  end  of  the  Pliocene  was  also  marked  by  disturbances,  and  most  of  the  asper- 
ites  seem  to  have  been  erupted  at  this  epoch.  The  ore  deposits  stand  in  close  relation  to  the  volcanic 
phenomena  and  are  probably  nearly  or  quite  all  Post-Pliocene. 

The  gold  belt  of  California  contains  -4i<ce7/a-beariug  beds  in  Mariposa  and  Tiioluume  Counties. 
This  shell  is  of  the  same  species  as  that  iu  the  Coast  Ranges,  and  the  first  known  upheaval  of  these 
mountains  was  contemporaneous  with  an  important  addition  to  the  Sierra  Nevada.  A  description  of 
various  forms  of  AuceUa  from  different  portions  of  the  world,  by  Dr.  C.  A.  White,  with  plates,  forms  an 
appendix  to  this  chapter. 

Descriptive  chapters  follow  dealing  with  the  various  districts  ,of  which  detailed  surveys  were  made. 
Each  of  these  districts  affords  special  facilities  for  the  study  of  some  special  topic.  The  Clear  Lake 
region  contains  fresh-water  Pliocene  beds,  and  iu  it  the  age  of  the  audesites  can  be  determined.  It 
also  contains  remarkable  areas  of  volcanic  glass.  '  At  Sulphur  Hank  cinnabar  is  being  precipitated  from 
heated  waters  largely  by  the  action  of  ammonia.  At  Knoxville,  besides  the  ore  deposits,  there  are 
admirable  opportunities  for  determining  the  age  of  the  raetamorphic  rocks  and  for  studying  the  process 
of  alteration.  At  New  Idria  the  non-conformity  between  the  metamorphic  rocks  and  the  Chico  and  the 
continuity  between  the  Chico  and  Tejou  appear.  The  New  Almaden  mine  is  particularly  well  adapted 
for  the  study  of  the  structure  of  the  ore  deposits.  At  Steamboat  Springs  cinnabar  is  being  deposited 
without  the  complications  introduced  by  the  presence  of  ammonia. 

In  Chapter  XII  the  Great  Western,  Great  Eastern,  and  Napa  Consolidated  mines  are  described,  and 
in  the  next  chapter  more  or  less  information  is  given  concerning  each  of  over  fifty  minor  deposits  on 
the  Pacific  slope.  Some  of  these  have  been  productive  mines,  while  others  are  mere  prospects  or  possess 
only  a  geological  interest. 

A  general  discussion  of  the  deposits  described  follows,  including  the  enumeration  of  the  gangue 
minerals,  the  microscopical  character  of  ores,  etc.  It  appears  that  the  cinnabar  has  been  deposited 
solely  in  pre-existing  openings,  and  never  by  substitution  for  rock.  The  fissure  systems,  which  are 
always  present,  are  very  irregular,  and  deposits  cannot  be  conveniently  classified  according  to  existing 
systems.  A  new  descriptive  term,  "chambered  vein,"  is  suggested,  which  would  inclmlr  nearly  all 
the  deposits.  A  chambered  vein  is  defined  as  a  deposit  consisting  of  an  ore-bearing  fissure  and  of  ore 
bodies  contiguous  with  the  fissure  which  extend  into  the  country  rock.  It  appears  that  all  of  the 
deposits  described  have  probably  been  deposited  iu  the  same  way  from  hot  sulphur  springs. 

Chapter  XV  deals  with  the  processes  by  which  the  ore  has  been  dissolved  and  precipitated  in 
nature.  It  is  shown  by  experiment  and  analysis  that  cinnabar  unites  with  sodium  sulphide  in  various 
proportions,  forming  soluble  doublo  sulphides,  and  that  these  compounds  can  exist  in  such  waters  as  flow 


BRIEF  OUTLINE  OF  RESULTS.  xix 

from  Sulphur  Bank  ami  Steamboat  Springs  either  at  ordinary  temperatures  or  aboveihe  boiliug-poiut. 
Metallic  gold,  iron  pyrite,  copper  pyrite,  and  other  mii;orals  found  with  cinnabar  are  also  soluble  in 
the  same  solutions. 

A  discussion  of  the  origin  of  the  ore  concludes  the  investigation.  It  is  shown  that  the  quicksilver 
is  probably  derived  from  granitic  rocks  by  the  action  of- heated  sulphur  waters  which  rise  through  the 
granite  from  the  foci  of  volcanic  activity  below  that  rock. 

For  the  convenience  of  those  who  consult  the  report  the  separate  chapters  are  made  as  far  as  pos- 
sible independent  of  one  another,  a  plan  involving  a  certain  amount  of  repetition.  Further  to  facili- 
tate the  use  of  the  volume,  the  last  chapter  presents  a  summary  of  those  which  precede  it. 


GEOLOGY  OF  THE  QUICKSILVER  DEPOSITS  OF  THE 

PACIFIC  SLOPE. 


BY  GEORGE  F.  BECKER. 


CHAPTER  I. 

STATISTICS  AND  HISTORY. 

Relative  vaius  of  quicksilver. — The  exceptional  physical  and  chemical  properties 
of  quicksilver  give  this  metal  a  peculiar  position  in  the  markets  of  the  world, 
which  it  is  desirable  to  illustrate  by  comparison  with  that  of  other  metals. 
The  normal  price  of  a  metal  is  slightly,  and  only  slightly,  greater  than  the 
average  cost  of  production  ;  for  competition  forces  prices  towards  a  minimum 
and  in  every  industry  there  are  individual  establishments  which,  through 
errors  in  judgment  or  want  of  foresight,  work  at  an  actual  loss.  For  purposes 
of  comparison  it  is  fair  to  assume  that  the  average  cost  of  production  is  not 
far  from  90  per  cent,  of  the  average  price.  From  January,  1850,  to  Janu- 
ary, ISSfi,  the  average  price  of  quicksilver  may  be  taken  at  about  $50  a 
flask,  though  the  fluctuations  have  been  so  great  and  so  frequent  that  a  pre- 
cise mean  could  not  possibly  be  reached.  The  average  total  cost  has  prob- 
ably been  about  *  If),  or  say  81.30  a  kilogram.  It  costs  about  twenty-nine 
times  as  much  to  produce  a  kilogram  of  silver  and  four  hundred  and  sixty 
times  as  much  to  produce  a  kilogram  of  gold.  These  facts  afford  sufficient 
proof  that  quicksilver  is  a  far  more  abundant  metal  than  is  silver.  Were 
quicksilver  and  silver  produced  in  exactly  equal  quantities  and  were  the 

MON  XIII 1  1 


2  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

extraction  equally  expensive,  the  cost  of  production  would  be  substantially 
proportional  to  the  abundance  of  the  metals  in  nature.  The  weight  of  quick- 
silver produced  is  considerably  in  excess  of  the  weight  of  silver.  Were  the 
quicksilver  product  about  three-fifths  of  the  actual  amount  and  were  the 
richer  deposits  only  worked  as  a  consequence  of  this  restriction,  the  metal 
could  be  produced  still  more  cheaply.  The  cost  of  reduction  per  kilogram, 
however,  is  trifling  for  quicksilver,  but  very  considerable  for  silver.  Making 
due  allowance  for  this  fact,  it  appears  that  quicksilver  must  be  three  or  more 
times  as  abundant  in  nature  as  silver. 

The  quantity  of  metal  produced  bears  an  intimate  but  not  a  simple 
relation  to  the  selling  price.  Higher  prices  would  stimulate  the  production 
of  quicksilver,  but  restrict  consumption  for  certain  purposes  and  to  a  certain 
extent.  With  some  metals  decrease  of  price  brings  with  it  a  greatly  in- 
creased consumption,  but  this  has  not  hitherto  proved  to  be  the  case  with 
quicksilver,  which  is  employed  for  very  few  purposes  in  large  quantities. 
The  consequence  is  that,  in  comparison  with  the  quantity  produced,  quick- 
silver is'the  cheapest  of  metals;  or,  in  other  words,  the  value  of  the  total 
product  is  very  small.  The  total  weight  of  quicksilver  produced  in  the  past 
thirty-six  years  is  less  than  twice  as  great  as  that  of  silver,  but  the  total 
value  of  the  quicksilver  is  only  one-sixteenth  that  of  the  silver.  The  world 
has  yielded  nearly  one-sixteenth  as  much  gold  as  quicksilver  during  the  past 
thirty-six  years,  but  the  total  gold  product  is  worth  thirty  times  as  much  as 
that  of  quicksilver.  Tin  is  a  metal  sharing  some  properties  with  quicksilver, 
and,  if  one  compares  frozen  quicksilver  with  tin,  the  likeness  is  much  stronger. 
The  tin  produced  in  thirty-six  years  weighs  about  six  times  as  much  as  the 
quicksilver;  but,  because  the  demand  for  tin  is  insatiable,  the  price  remains 
sufficiently  high  to  make  the  total  value  of  the  tin  more  than  twice  as  great 
as  that  of  quicksilver. 

These  relations  may  be  succinctly  expressed  in  a  table  such  as  the  fol- 
lowing, which  gives  the  total  weights  and  values,  the  value  of  a  kilogram  of 
each  nu-tal,  and  the  relative;  quantities  when  gold,  silver,  and  quicksilver  are 
each  regarded  as  unity.  Silver  is  now  worth  much  less  than  the  mint  value; 
but,  for  a  great  part  of  the  period  which  has  elapsed  since  1850,  this  metal 


VALUE  A^D  USES. 


has  been  at  a  slight  premium.  The  mint  value  is  thus  sufficiently  close  to 
the  average  for  the  present  purpose.  The  data  as  to  the  gold  and  silver 
products  are  compiled  from  figures  given  by  Dr  Soetbeer  and  Dr.  Kimball.1 
The  figures  for  tin  are  only  approximations,  but  are  close  enough  for  the 
purpose.2  In  estimating  the  total  quicksilver  I  have  supposed,  with  Mr. 
Kandol,  thai;  the  average  yearly  product,  besides  that  of  Almaden,  Idria, 
and  California,  is  2,000  flasks.3  The  mean  value  is  assumed  at  $50  a  flask. 

The  world's  product  of  four  metals  from  January,  1850,  to  January,  1886. 


Total  product. 

Total  value. 

Value  per  kilogram. 

Kilograms. 

Approximate  ratios. 

Dollars. 

Approximate  ratios. 

Dollars. 

Approximate  ratios. 

Gold  

6,  481,  922 
58,051,906 
101,  300,  000 

0:0,  ooo,  ooo 

1. 

8.9 
15.6 
95.6 

0.11 
1. 
1.74 
10.7 

0.064 
0.57 
1. 
6.12 

4,309,879,161 
2,413,203,111 
146,  800,  0.  0 
322,403,0,0 

1. 
0.56 
0.03 
0.17 

1.7!) 
1. 
0.00 
0.13 

29.3 
10.4 
1. 
2.2 

601.  60 
41.5676 
1.45 
0.  52 

1. 
0.083 
0.002 
0.0008 

10. 
1. 
0.035 
0.013 

4.'8. 
28.7 
1. 
0.36 

Quicksilver.  .. 
Tin  ...... 

us=s  for  quicksilver. — The  low  value  of  quicksilver,  which  is  abnormally  small 
considering  the  comparative  rarity  of  the  metal,  is  due  to  its  restricted  use. 
It  is  true  that  the  number  of  purposes  to  which  quicksilver  is  applied  is 
very  great;  but  most  of  these  applications  imply  the  consumption  of  trifling 
quantities  of  the  metal.  A  single  flask  of  quicksilver  in  the  form  of  mir- 
ror-backs, thermometers,  or  medicines  goes  a  long  way.  The  great  mass 
of  the  metal  is  employed  in  the  amalgamation  of  ores  and  in  the  manufact- 
ure of  vermilion.  As  only  certain  silver  ores  can  be  economically  amalga- 
mated, the  demand  for  this  purpose  fluctuates  greatly.  The  bullion  of  the 
Comstock  was  all  extracted  by  this  process,  but  amalgamation  is  not  appli- 
cable to  any  of  the  ores  of  Leadville.  The  demand  for  vermilion  also  is 
limited  by  the  competition  of  other  red  pigments.  A  few  years  since,  Mr. 
J.  A.  Baur,  of  San  Francisco,  devised  a  means  for  the  extirpation  of  phyl- 
loxera, which  consists  in  intimately  mixing  clay  with  quicksilver  (or  "ex- 

1  Report  of  the.  Director  of  the  Miuf,  18-i;i,  pp.  Ki'J  and  171. 

2  They  arc  estimated  from  data  contained  in  Mr.  J.  A.  Phi  Hi  JIN'S  Ore,  Deposits  and  statistics  which 
I  gathered  at  the  Paris  Exposition  of  1H7S  (Reports  of  the  United  States  Commissioners,  vol.  4). 

::  This  for  the  later  years  is  much  too  small.    The  Tuscan  mines  arc  said  to  be  producing  aliout  six 
hundred  flasks  a  month. 


4  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

tinguishing"  quicksilver  with  clay)  and  adding  this  material,  which  is 
substantially  blue  mass,  to  the  soil  in  which  the  vines  are  planted.  The 
process  seemed  at  first  successful,  but  subsequently  failed  to  give  the  de- 
sired result.  Prof.  E.  W.  Hilgard1  has  experimented  on  the  process  and 
found  it  entirely  successful  when  properly  carried  out.  No  lead  or  oil  should 
be  added  to  the  quicksilver,  and  the  soil  either  must  be  sandy  or,  after  im- 
pregnation with  mercury,  must  be  warmed  in  a  hot  sun  or  by  artificial 
means,  to  saturate  it  with  mercurial  vapor.  Should  this  process  be  widely 
introduced  it  would  greatly  enlarge  the  market  for  quicksilver  and  would 
correspondingly  benefit  the  mining  industry. 

Comparison  between  various  mining  regions.  -  Quicksilver  lias  beeil  produced  ill   large 

quantities  in  but  few  localities.  The  principal  productive  regions  have  been 
Almaden  in  Spain,  Idria  in  Austria,  Kwei-Chau  in  China,  Huancavelica  in 
Peru,  and  California.  Italy  has  yielded  a  little  quicksilver  for  a  long  time 
and  a  considerable  number  of  localities  elsewhere  have  had  a  temporary  .or 
local  importance,  but  none  is  to  be  compared  with  those  enumerated  in  the 
last  sentence.  Peru  is  now  producing  no  quicksilver  and  the  Chinese  pro- 
duction is  small,  but  it  is  certain  that  the  Chinese  deposits  are  not  exhausted 
and  Huancavelica  may  possibly  resume  production  when  the  conditions  for 
intelligent  exploitation  are  better. 

Such  geological  interest  as  attaches  to  the  occurrence  of  exceptionally 
large  quantities  of  cinnabar  is  independent  of  the  question  of  future  produc- 
tiveness, and  a  few  historical  notes  on  the  past  yield  may  be  welcome  to  the 
reader. 

The  great  quicksilver  mine  of  the  world  is  Almaden,  which  has  been 
worked  since  at  least  415  years  before  the  Christian  era,  and  perhaps  still 
longer.  What  quantity  of  ore  was  extracted  from  it  in  ancient  times  and 
in  the  Middle  Ages  there  is  no  means  of  knowing,  further  than  that  Pliny 
reports  1  0,000  pounds  of  cinnabar  a  year  as  brought  to  Rome  from  Almaden 
(Sisapo).  The  product  was  certainly  never  large  until  the  amalgamation 
process  was  invented  in  1557.  Since  that  time  the  product  has  increased 
pretty  steadily,  and  the  output  since  1850  is  nearly  equal  to  that  of  the 
entire  eighteenth  century.  The  deposit  is  said  to  grow  richer  in  depth 


'Science,  vol.  G,  ldcT>,  t>.  4'.i7,  anil  vol.  7.  Hs<i,  p.  .K\->. 


PRINCIPAL  DISTRICTS  COMPARED. 


and  is  certainly  far  from  being  exhausted  ;  on  the  contrary,  in  the  metliod 
of  exploitation  followed,  large  pillars  of  ore  are  left  as  reserves.  The  con- 
tents of  these  reserves  would  be  sufficient  to  yield  the  usual  product  for 
very  many  years  to  come,  but  no  autlionUiUve  statement  of  the  total  amount 
of  metal  contained  in  them  has  been  made.  The  total  recorded  yield  is 
nearly  four  million  flasks. 

The  deposits  of  Idria  wore  discovered,  according  to  some  authorities, 
in  1490;  according  to  others,  in  1497.  Since  1580  they  have  been  worked 
by  government  officials  for  public  account.  The  mines  and  reduction 
works  are  extremely  well  managed,  and  the  greatest  additions  which  have 
been  made  to  the  technology  and  geology  of  quicksilver  have  come  from 
this  establishment.  The  mine  is  worked  at  a  large  profit,  and  in  1880  the 
director,  that  eminent  mining  geologist,  the  late  M.  V.  Lipold,  stated  with 
evident  and  justifiable  pride  that  the  average  clear  profit  to  the  state  for  the 
preceding  sixty  -five  years  had  been  3(55,000  florins1  per  annum.  The  profit 
in  1874  lacked  but  a  few  thousand  of  2,000,000  florins,  and  in  only  three 
of  the  sixty-five  years  was  there  a  deficit.  As  at  Ahnaden,  the  deposit 
grows  stronger  in  depth,  and  in  1880  the  reserves  were  known  to  contain 
no  less  than  30,142,000  kilograms,  or  873.504  flasks  of  75  Spanish  pounds. 
The  total  known  product  up  to  January,  188(5,  is  over  a  million  and  a  half 
of  flasks;  but  no  data  were  preserved  for  some  forty  years  during  the  term 
which  had  elapsed  since  work  began.  The  product  of  Idria  lias  been  about 
three-eighths  of  that  of  Almaden. 

In  northern  Italy,  at  no  great  distance  from  Idria,  are  several  deposits, 
of  which  the  principal  is  the  Vallalta.  There  is  also  a  series  of  mines  in 
Tuscany  stretching  along  the  western  coast  of  Italy.  Some  of  the  de- 
posits arc  of  considerable  commercial  importance.  The  product  is  given 
I  iv  Mr.  A.  d'Achiardi  as  follows,  in  kilograms: 


Tuscan  IIUIH-M  . 


1800. 


3,  500 
30,256 


1870. 


if.,  (mil 

31,192 


1878. 


3,080 


1879. 


129,  COO 
2,464 


1880. 


nr>,  94D 


1  Austrian  paper  money.     A  florin,  silver,  is  $d.-l-J7-'.     The  value  of  paper  fluctuate)*.     At  15  eeuts 
the  above  yearly  profit  would  be  sit',1, •>:>(). 


6  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

This  table  serves  to  show  how  the  quicksilver  mining  industry  has 
been  transferred  from  Vallalta  to  Tuscany.  The  sum  of  the  products  here 
given  for  five  years  is  13,087  flasks,  Spanish  standard,  or  an  average  of 
2, 01 7  flasks  a  year.  From  1850  to  18GO  ihe  average  was  probably  con- 
siderably lower.  Since  1880  it  has  been  greater.1 

The  ore  deposits  of  Huancavelica,  in  Peru,  were  discovered  soon  after 
the  invention  of  the  amalgamation  process.  There  are  over  forty  deposits 
in  the  district,  but  the  principal  mine  was  the  Santa  Barbara.  This  mine 
was  sometimes  worked  by  the  state  and  was  sometimes  leased  to  private 
parties  on  condition  that  the  metal  obtained  should  be  made  over  to  the 
state  at  a  fixed  price.  Stealing,  however,  was  prevalent  to  such  an  extent 
that  merchants  flocked  to  Huancavelica  with  no  inconsiderable  sums  of 
money  to  buy  from  miners  and  foremen  the  metal  which  it  was  their  duty 
to  turn  into  the  treasury.  The  technical  management  seems  to  have  been 
as  bad  as  the  business  administration  of  this  property,  and  there  can  be 
little  doubt  that  skillful  and  honest  work  would  have  secured  a  far  larger 
total  output,  With  all  disadvantages,  the  Santa  Barbara  mine  alone  yielded 
to  the  state  about  as  much  quicksilver  as  has  thus  far  been  produced  in 
California. 

Of  the  mines  of  Kwei-Chau,  in  China,  very  little  is  known.  Baron  von 
Richthofen,  however,  a  most  excellent  judge,  believed  this  district  to  be 
the  richest  quicksilver  region  in  the  world. 

Table  of  products.. —  I  have  thought  it  worth  while  to  bring  the  figures  repre- 
senting the  known  production  of  the  more  important  quicksilver  regions 
together  for  comparison  in  the  following  table.  The  figures  for  Almaden 
are  taken  from  a  memoir  by  Mr.  II.  Kuss2  and  data  furnished  by  Mr.  J.  B. 
Randol.3  In  Mr.  Kuss's  table  of  product  for  1800  to  1875,  there  is  a  misprint 
amounting' to  1,000,000  kilograms.  Mr.  Randol's  data  prove  that  the  total 
for  this  period  given  by  Mr.  Kuss  is  correct  and  that  the  misprint  is  between 
1  soo  and  1850.  The  product  of  Almaden  for  1 885  was  47,021.  flasks.  The 

1  According  to  data  furnished  to  me  l>y  the  superintendents  of  the  Siele  and  the  Cornachitio  mines 
(the  only  oues  at  work,  so  far  as  I  can  ascertain,  in  Tuscany),  the  average  product  for  the  five  years 
1881  to  1885  was  5,789  flasks.  The  product  for  ls-if,  was  7,478  ilastks. 

'Anuales  den  mini's,  vol.  13,  1878,  p.  150. 

'Mineral  Resources  IT.  S.  1883  and  1884,  p.  492. 


PRODUCTION.  7 

data  for  Idria  up  to  January  1,  1880,  are  from  an  official  publication.1  The 
amount  of  quicksilver  definitely  known  to  have  been  produced  in  the  six- 
teenth century  is  2,934,000  kilograms.  "At  the  beginning  of  the  seven- 
teenth century  the  production  rose,  amlrbeginning  with  1612,  the  product 
was  for  some  years  1,680  metrical  centals  annually.  During  the  later  years 
the  average  yearly  product  was  1,120  centals."  I  shall  assume  that  this 
latter  and  smaller  output  extended  over  seventy  years.  This  assumption, 
in  combination  with  the  figures  just  given,  leads  to  the  total  product  prior 
to  1800  which  appears  in  the  table.  The  production  of  Idria  from  1800 
onwards  is  from  exact  official  figures.2  The  data  for  Huancavelica  are 
taken  from  Mr.  M.  E.  de  Rivero's  memoir  on  the  district.3 

The  data  from  1571  to  1790  are  for  the  Santa  Barbara  mine  alone, 
from  which  the  state  received  1,040,469  quintals  30  pounds  15  ounces  dur- 
ing this  period.  The  known  product  subsequent  to  1790  includes  other 
mines  as  well  as  the  Santa  Barbara. 

Product  of  the  principal  dint  rifts,  in  Spanish  flasks  of  75  Spanish  pounds  or  34.507  kilo- 

gramg. 


First  record. 

Up  to  1700. 

l~UOto  1800. 

1800(01850. 

1  .-'Mi  to  1880. 

Total  to  Jan.,  1886. 

Year. 
1564 

517  084 

1  22]  477 

1  091  975 

1  135  576 

3  965  812 

Idria  

1B28 

S99  861 

608  743 

349  99g 

301  549 

1  552  379 

1571 

881  867 

543  649 

75  604 

1  501  113 

1850 

1  429  346 

1,799,412 

2,  373,  862 

1,408,905 

2,  806,  471 

8,  448,  650 

Discovery  of  California  deposits. —  In  the  last  century  Mexico  was  almost  entirely 
dependent  upon  Spain  and  Peru  for  the  quicksilver  needed  for  the  amalga- 
mation process.  As  this  process  was  indigenous  to  Mexico  and  was  also  a 
national  industry  peculiarly  suited  to  her  resources,  it  was  felt  to  be  specially 

1  Das  k.  k.  Quecksilberwerk  xu  Idri.i  in  Krain,  1881. 

4  In  tins  memoir  already  referred  to,  Lipold  gives  the  product  of  the  mine  from  1800  to  the  end  of 
1879  at  78,430  metrical  centners,  which  is  ^27,43-2  flasks.  The  present  director,  Mr.  Job.  Novak,  has 
been  good  enough  to  supply  me  with  the  following  figures,  in  flasks: 


1880. 

1881. 

1882. 

1883. 

1884. 

1885. 

1886. 

Product  of  Idria  

10  510 

11  333 

11  65° 

DMemoria  sobre  ul  rico  mineral  de  azoguo  do  Ituaucavelica,  Lima,  1848. 


UNIVERSITY 


8  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

desirable  that  quicksilver  mines  should  be  developed  on  her  own  soil. 
Accordingly,  as  far  back  as  1783,  quicksilver  mining  was  made  the  subject 
of  special  legislation.  A  quicksilver  fund  was  established  out  of  the  public 
revenues  for  the  purpose  of  promoting  the  discovery  and  development  of 
quicksilver  mines.  On  every  hundred  weight  of  the  metal  produced  a  bounty 
was  paid,  and  a  large  sum  was  offered  to  those  who  should  succeed  in  pro- 
ducing a  specified  quantity  annually.1 

Not  only  are  there  many  skillful  miners  and  prospectors  in  Mexico, 
but  so  universal  is  the  interest  in  the  subject  that  a  knowledge  of  ores  has 
become  almost  instinctive  among  Mexicans.  It  would  be  supposed  that, 
when  their  natural  acuteness  in  mineralogy  was  sharpened  by  the  promised 
rewards,  some  of  the  many  cinnabar  deposits  of  California  would  have 
been  discovered  within  a  few  years  after  the  promulgation  of  the  edicts  of 
1783;  but  this  did  not  happen  for  more  than  sixty  years. 

It  has  been  asserted  that  the  California  Indians  knew  of  the  cinnabar 
of  New  Almaden  and  used  it  for  paint  long  before  the  Spanish-American 
immigrants  became  acquainted  with  it.  The  evidence  on  this  point  seems 
to  be  quite  inconclusive,  and  it  is  not  impossible  that  the  incident  is  bor- 
rowed from  the  history  of  Peru,  where,  as  all  historians  are  agreed,  the 
subjects  of  the  Incas  were  familiar  with  the  use  of  vermilion.  The  same 
story  has  been  related  within  a  few  years  of  Nevada  Indians.  It  is  hard  to 
say  whether  it  is  more  probable  that  the  aborigines  repeated  the  same  series 
of  discoveries  in  personal  adornment  at  these  three  points  or  that  the  whites 
have  forced  the  same  characteristic  anecdote  into  service  a  number  of  times, 
with  changes  of  names  and  dates.  It  has  also  been  assorted  that  the  Spanish 
Californians  excavated  cinnabar  at  New  Almaden  and  used  it  to  paint  the 
mission  church  at  Santa  Clara.  The  occurrence  was  certainly  known  as 
early  as  1824,  when  Antonio  Sufiol  and  Luis  Chaboya  erected  a  mill  on  a 
neighboring  stream  and  endeavored  to  extract  silver  from  the  cinnabar.  A 
second  attempt  of  the  same  kind  was  made  in  1835.  Late  in  1845  Andreas 
Castillero,  a  Mexican  officer  who  was  on  a  journey  to  Slitter's  Fort,  passed 
through  Santa  Clara.  The  mysterious  ore  was  shown  to  him,  and  he  is 

1  The  notes  on  tlto  history  of  tin;  discovery  of  quicksilver  in  California  urr  derived  from  the  testi- 
mony in  the  case  of  The  I 'mini  States  ''<s'-  Andreas  Cast!  Hero,  disci  dod  by  I  lie  Snin'eine  Court,  December 
term,  ISfri.  (Black's  S.  C.  R.,  vol.  2.) 


DISCOVERY  OF  NEW  ALMADEN.  9 

said  to  have  visited  the  mines.  He  shortly  afterwards  returned,  and  what 
occurred,  according  to  the  testimony  of  Jacob  P.  Leese,  is  so  curious  and 
interesting-  as  to  be  worth  ([noting: 

About  the  latter  part  of  November,  ofHrst  of  December,  1845,  I  went  into  the 
mission  of  Santa  Clara  to  dine  with  Padre  Real,  of  the  mission.  Mr.  C.istillero  was 
there.  Our  general  conversation  through  dinner  was  about  this  mine  and  of  experi- 
ments which  Castillero  had  beeu  trying  to  find  out  what  the  mineral  was.  He  made 
a  remark  and  said  he  thought  he  knew  what  it  was.  If  it  was  what  he  supposed  it 
was  he  had  made  his  fortune.  We  were  anxious  to  know  what  it  was.  He  got  up 
from  the  table  and  ordered  the  servant  to  pulverize  a  portion  of  this  ore.  After  it 
was  pulverized  he  ordered  the  servant  to  bring  in  a  hollow  tile  full  of  lighted  coals. 
He  took  some  of  the  powdered  ore  and  threw  it  on  the  coals.  After  it  got  perfectly 
hot  lie  took  a  tumbler  of  water  and  sprinkled  it  ou  the  coals  with  his  lingers.  He 
then  emptied  the  tumbler  and  put  it  over  the  coals  upside  down ;  then  took  the  tum- 
bler off  and  went  to  the  light  to  look  at  it;  then  made  the  remark  that  it  was  what 
he  supposed  it  was— "quicksilver."  He  showed  all  who  were  there  the  tumbler,  and 
we  found  that  it  was  frosted  with  minute  globules  of  metal,  which  Castillero  collected 
witli  his  linger  and  said  it  was  quicksilver.  He  then  said  to-morrow  he  would  test  it 
thoroughly  and  find  out  what  it  was  worth.  He  considered  it  very  rich  on  account  of 
the  weight  of  the  ore,  and  if  it  proved  as  rich  as  the  quicksilver  mines  in  Spain,  that 
the  Mexican  government  had  ottered  to  any  one  for  the  discovery  of  such  a  mine  in 
the  Republic  of  Mexico  one  hundred  thousand  dollars. 

Like  so  many  Mexican  practices,  this  test  has  a  very  quaint  and  medi- 
eval character,  but  it  was  nevertheless  founded  upon  correct  principles  and 
was  calculated  to  afford  a  demonstration  of  the  presence  of  quicksilver 
without  the  use  of  reagents  which  were,  perhaps,  inaccessible  to  Castillero. 
Ity  the  use  of  glowing  coals  and  water  he  effected  a  steam-roasting  of  the 
ore,  which  was  sure  to  liberate  metallic  mercury  if  cinnabar  was  present, 
and  the  cold  wet  tumbler  acted  as  an  efficient  closed  condenser.  The  test 
was,  in  fact,  equivalent  to  the  ordinary  blow-pipe  test  in  a  closed  tube,  the 
action  of  alkaline  reducing  agents  being  replaced  by  that  of  steam. 

Castillero  laid  claim  to  the  property  as  a  mine  containing  silver,  gold, 
and  quicksilver.  He  either  had  difficulty  in  thinking  of  a  mine  contain- 
ing no  precious  metals  or  thought  it  expedient  to  make  his  claim  sufficiently 
broad.  There  was  nothing  unnatural  in  the  association,  for  the  three  metals 
are  found  together  at  almost  innumerable  points  in  America  and  Europe. 
In  the  opinion  of  the  Supreme  Court  of  the  United  States,  indeed,  this  as- 
sociation constitutes  an  inconsistency  which  tended  strongly  to  impair  the 
validity  of  the  entire  claim,  but  judicial  geology  is  well  known  to  belong 


10  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

to  a  special  school.  Work  was  begun  almost  immediately  under  Castil- 
lero's  direction,  gun-barrels  being  used  ;is  retorts.  These  insignificant 
reduction  works  have  now  grown  to  very  imposing  dimensions,  but  the 
ijiiantity  of  ore  in  sight  is  no  longer  so  satisfactory. 

The  other  deposits  of  California  have  been  found  in  part  by  systematic 
prospecting  and  in  part  by  accident.  The  Redington  mine  was  discovered 
in  making  excavations  for  a  highway.  The  Sulphur  Bank,  as  its  name  im- 
plies, was  worked  for  sulphur  for  some  time  before  the  presence  of  the  un- 
derlying cinnabar  was  suspected.  The  very  high  prices  which  quicksilver 
brought  in  1X74  and  1X75  greatly  stimulated  production  and  the  discovery 
of  deposits.  None  of  those  found  grows  richer  as  depth  from  the  surface 
increases,  but  most  of  them  are  very  imperfectly  developed,  and,  as  will  be 
shown  in  subsequent  chapters,  this  feature  depends  upon  peculiarities  of  the 
systems  of  fissures  connected  with  the  ore  deposits,  not  upon  characteristics 
of  cinnabar.  It  is  by  no  means  impossible  that  great  deposits  of  cinnabar, 
comparable  with  those  of  Idria,  if  not  with  those  of  Almaden,  still  exist  in 
California.  None  such,  however,  is  now  known  and  the  amount  of  ore 
in  sight  is  not  great. 

production  in  California. — The  following  table  of  production  of  the  mines  of 
California  has  been  compiled  from  year  to  year  by  Mr.  J.  B.  Randol  and  is 
well  known  to  those  interested  in  the  subject. 


PRODUCT  OF  CALIFORNIA. 


11 


Production  of  quid-nil rcr  on  the  Pacific  Slope,  in  flasks  o/"7»>i  pounds  avoirdupois. 


Years. 

J 

<•  d 
^ 

r 

New  I.lrin. 

| 
te 
.9 

1 

Sulphur 
Bauk. 

| 
J 

- 

.  

Great  "West- 

iiu. 

Pope  Valley. 

l| 

a-o 

S 

, 

Q 

M 
o 
HI 

£^ 

4 

I 
5 

1850            .          

7  ~-.\ 

0  =      ( 

}         rt 

' 

fW  <*« 

1851 

'^7  779 

1  P.      1 

tJ 

a  a 

1H52  

in  901 

£2 

a 

g_C 

18J3 

'VI     -1^ 

!  r 

a 

il 

lh.-,l       

.-  " 
I-  " 

ij 

il 

1855 

29  U" 

*"5 

3! 

*a 

185G       

°7  138 

0    1 

£  = 

§•0 

1857  

28  °04 

?-i  t 

jrl 

?1 

1858        

°r>  7111 

I-oi.2-, 

-  =  = 

^  > 

|| 

1859  

1,294 

.'.  "  i. 

11 

|a 

I860 

7  Otil 

~i| 

si 

§•2 

18CI  

34  429 

If! 

^3 

A 

1802  

39  671 

a  «  o 

444 

*'t 

^g 

1863  

32  803  ' 

III 

852 

P"-" 

1864    

42  489 

=  SS 

1  914 

c-a 

800 

00 

"  m 

1865                   .... 

47  194 

5  %.— 
1  ~ 

3  545 

|| 

2£ 

1806 

35  150 

6  5°5 

2  '54 

c~ 

S3 

1867  

24,  461 

11  4«:i 

7,862 

>5 

£.- 

*a 

1868  

25,  628 

1"  VI) 

8,686 

U 

1  122 

•0  0 

®  E 

1869  

16,  898 

]o  :Mr> 

S,  018 

|4 

1  580 

§1 

«  fe  * 

1870  

14,  423 

9  KXK 

4,  516 

|| 

1,220 

0 

1871  

18,568 

8  180 

2  128 

!* 

1  970 

"2  a 

1872  

is  r,7i 

8  171 

3  046 

p. 

]  830 

IBS 

S  a  S 

1873  

11,042 

3,294 

340 

1  955 

?£S 

1874  

9,084 

6  911 

6,678 

573 

1 

1  12' 

1  645 

1  743 

|S.? 

1875  

13,  648 

8  432 

7,513 

5  372 

3  342 

3  3M 

1  940 

1  927 

533 

1876 

20  549 

7  <>7o 

9  183 

8  367 

7  381 

4  3°2 

1877 

23  906 

6  316 

9  399 

10  993 

6  241 

1878  

15,  852 

5,138 

6,686 

9,465 

9,072 

4  963 

1  075 

3  049 

1  534 

1879  

"0  514 

4  4"5 

4  S16 

9  249 

15  540 

6  333 

1  3OI> 

1880  . 

23  465 

3  "09 

2  139 

10  706 

6  67n 

6  442 

27ri 

1881  

26,  060 

2  775 

2  194 

11   152 

5  228 

6  241 

5  55° 

1882  

28  070 

1,953 

2   171 

;"j  Oil 

1  138 

5  179 

6  812 



28,00* 

i  i;i'.; 

I,SM 

2,612 

84 

3,869 

5  £90 

1684  

20,  OlO 

1,  025 

881 

890 

1,179 

3,292 

4  307 

1885  

21  400 

1   144 

J  385 

1  296 

35 

3  469 

1886  

18,000 

1,406 

409 

1,449 

1  949 

5  247 

Total  ... 

853,259  ' 

126,  099 

97,  637 

77  138 

55  910 

56  761 

18  097 

45  216 

1  Including  .Ktn;i. 


12 


QUICKSILVER  DEPOSITS  OF  TEE  PACIFIC  SLOPE. 


Production  of  quicksilver  on  the  Pacific  Slope,  in  flasks  o/7Gi  pound*  a 


STenrs. 

Oceanic. 

Oakland. 

California. 

Great  East- 
ern. 

Snnderland. 

Cloverdale. 

Abbott. 

Manhattan. 

Various 
mines.' 

Total  yearly 
production 

of  Califor- 
nia mines. 

S       t 

7,723 

8 

27,  778 

a 

4,  099 

20,  000 

OO    OQJ 

I 

::n,  1104 

.§» 

3  e5K 

33,  000 

£.5 

2,  SO'.' 

30,  000 

1  « 

2X,  1:0-1 

S3 

5,239 

31,  000 

•—  > 

11.7CIC 

13,000 

2~ 

2,939 

lll.OOi 

2  S 

571 

35,  00. 

It 

1,  8*5 

42,  OC( 

o-S   •> 

6,  K7G 

40,  5J 

1864 

S  ^ 

2,280 

47,  48i 

2,201 

53,  00( 

5  I 

2,  621 

46,  55( 

1867 

11 

3,  1K4 

47,  00( 

>  c 
B 

ns 

47,  72* 

a 

33,81 

C   rt 

30,  07' 

840 

81,881 

1 

31   6-> 

1873 

p. 

3,  'J7fi 

27,  041 

'.'7,  75( 

1875 

412 

0) 

|M 

3,747 

so,  -:,( 

1876  

2,358 

2,160 

9f5 

387 

1,570 

1.0J8 

1,436 

976 

2,585 

75,  07< 

1877           

2,  575 

1,385 

1,516 

505 

735 

1,291 

830 

439 

1,234 

79,  39t 

1878 

1  679 

1  (J'5 

1  610 

1  366 

472 

116 

158 

C3,  K( 

779 

1  110 

1  455 

18 

101 

73,68- 

166 

422 

1  *>79 

59,92 

1881 

1  065 

208 

376 

60,  F5 

1882 

2  124 

211 

52,  73 

1883 

1  609 

lul 

40,  72 

1884 

332 

7 

31,91 

1886 



89) 

32,  07 

1886  

735 

780 

29,98 

Total 

7  391 

6  831 

5  653 

11,  775 

2,  777 

2,661 

2,  -Hi 

1,415 

64,  353 

1,451,37 

1 

'The  column  of  various  mines  includes  the  product  of  the  Buckeye,  Mt.  Jiirkxiiti,   Huron,  Ite.lla  Union,  American, 
Porter,  Wall  Street,  Rattlesnake,  Kentuck,  and  other  mines.    This  column  includes,  iu  1882,  50  flasks  produced  in  Oregon. 


GEOGRAPHICAL  POSITION. 


13 


Geographical  position  of  mines. — The  following  list  will  enable  the  reader  to  find 
some  of  the  mines  mentioned  in  the  preceding  table,  as  well  as  others  to  be 
referred  to  later,  on  the  sketch-map  of  California  (PI.  I)  and  to  appreciate 
approximately  the  geographical  position  of  others: 

Distribution  of  quicksilver  mines. 
(Mines  marked  M  are  iu  the  Mayacmas  district.) 


Abbott,  Colusa  county. 
Altooua,  Trinity  count}'. 
American  (M),  Lake  county. 
Bacon  (M),  Lake  county. 

Bella  Union,  Napa  county. 

• 
Buckeye,  Colusa  county. 

California  (Reed),  Yolo  county. 
Cerro  Bonito,  Fresno  county. 
C'lovcnlalc  (M),  Sonoma  county. 
Euriquita,  Santa  Clara  county. 
Guadalupe,  Santa  Clara  county. 
(Ircat  Eastern,  Sonoma  county. 
Great  Eastern  (M),  Lake  county. 
Great  Western  (M),  Lake  county. 
Kentucky  (M),  Sonoma  county. 
Little  Panocbe,  Fresno  county. 
Los  Prietos,  Santa  Barbara  county. 
Manhattan,  Napa  county. 
Man/anita,  Colusa  county. 


Mt.  Jackson,  Sonoma  county. 
Napa  Consolidated,  Napa  county. 
New  Aluiaden,  Santa  Clara  county. 
New  Idria,  Fresno  county. 
Oakland  (M),  Sonoma  county. 
Oceanic,  San  Luis  Obispo  county. 
Ocean  View,  San  Luis  Obispo  county. 
Picacbo,  San  Benito  county. 
Pope  Valley,  Napa  county. 
Rattlesnake  (M),  Sonoma  county. 
Redington,  Napa  county. 
Reed  (same  as  California),  Yolo  county. 
San  Juan  Bautista,  Santa  Clara  county. 
St.  John,  Solano  county. 
Stayton,  San  Benito  county. 
Steamboat  Springs,  Ormsby  county,  Nev. 
Sunderland.  San  Luis  Obispo  county. 
Wall  street  (M),  Lake  county. 


Other  interesting  statistical  information  with  reference  to  quicksilver 
may  be  found  in  the  Mineral  Resources  issued  bv  the  U.  S.  Geological 

f  O 

Survey. 


CHAPTER  II. 

NOTES  ON  FOREIGN  OCCURRENCES   OF  QUICKSILVER, 

There  are  few  districts  besides  those  of  the  Pacific  Slope  in  which  mer- 
curial ores  are  met  with  in  such  abundance  as  to  be  of  great  commercial 
importance.  The  Almaden  mines,  in  Spain,  take  the  first  rank,  and  those 
of  Idria,  in  southern  Austria,  have  yielded  and  will  continue  to  yield  a  con- 
siderable product.  Several  thousand  flasks  a  year  are  also  extracted  from 
the  Tuscan  mines.  China  now  produces  little  quicksilver,  though  she  for- 
merly exported  it,  besides  supplying  the  home  demand.  This  is  not  due  to 
the  exhaustion  of  the  mines,  and  there  seems  to  be  good  reason  to  suppose 
that  the  deposits  of  Kwei-Chau  are  of  great  extent  and  value.  Peru  has 
yielded  very  large  quantities  of  quicksilver  in  former  times,  but  the  mines 
are  in  part  exhausted  and  in  part  have  been  ruined  by  bad  mining.  While 
the  number  of  highly  productive  localities  is  small,  the  localities  in  which 
ores  occur  are  very  numerous,  and  many  of  these  have  been  of  temporary 
or  local  importance.  The  geological  interest  attaching  to  a  locality  is  not 
dependent  upon  the  amount  of  metal  which  it  has  furnished  to  the  markets 
of  the  world,  but  upon  the  relations  between  cause  and  effect  which  the 
occurrence  serves  to  elucidate,  and  a  brief  review  of  the  deposits  known  to 
exist  away  from  the  Pacific  Slope  will  form  the  fittest  introduction  to  the 
subject  of  this  memoir. 

It  will  appear  in  the  subsequent  chapters  that  nearly  every  mineral 
association  and  mode  of  occurrence  known  to  exist  elsewhere  is  repeated  in 
California  and  Nevada,  so  that  the  mercurial  deposits  of  the  Pacific  Slope 
admirably  represent  those  of  the  world  so  far  as  they  are  known. 

I  have  made  no  systematic  endeavor  to  exhaust  geological  literature 
with  reference  to  foreign  occurrences  of  mercurial  ores,  though  it  is  certain 
that  no  very  important  deposits  have  escaped  me.  I  have  sought  to  compile 

14 


IT.  S  .  GEOLOGICAL    SUKVEY. 


180'  ISO'  IMP'  130  I2O  110°  100'  90'  80'  »•  '  60'  SO*  4O*  3O"  SO 


DISTRIBUTION     OF     Q 

TH  HOI'  OHO  I 
Districts  which  are  or  have  bi-rn  pi-odnctivc  •         llislrii-l 


MONOGRAPH   XIII,  PL.  II. 


II,-  jo-  go'  'iO  So'  60  10'  flu  90*  100'  110*  J£0°  130'  1W  1*0*  160' 


:  •  K  s  i  L.V.K  R  D  T:  POST  ri^  s 

;THE:  WOULD 

which  OIT  has  been  clrU-cledO         C  ouucrtin^'  lines 


OftO.K Becker, Geologist  in  charsfe. 


01 

UNIVERSITY 


NORTH  AMERICAN  LOCALITIES.  15 


notes  on  comparatively  little-known  deposits  rather  than  on  those  which 
have  been  most  frequently  described,  and  I  have  altogether  omitted  a  con- 
siderable number  of  unimportant  occurrences  in  Germany  and  Austria,  de- 
scriptions of  which  are  readily  accessibte-in  standard  works  on  mining 
geology.  Two  reviews  of  the  quicksilver  deposits  of  the  world  have  been 
of  great  use  to  me.  These  are  by  Mr.  A.  Noggerath1  and  Prof.  A.  d'Achiardi2 
respectively. 

The  sketch-map  of  the  world  (PI.  II)  accompanying  this  chapter  will  be 
of  some  assistance  in  following  the  text,  but  its  principal  purpose  is  to  illus- 
trate the  larger  features  of  the  distribution  of  cinnabar. 

NORTH    AMERICA. 

Away  from  the  Pacific  Slope  the  United  States  possesses  no  known 
deposits  of  cinnabar.  There  is,  indeed,  a  settlement  named  Cinnabar  near 
the  Yellowstone  Park,  but  I  am  informed  that  no  mercuric  sulphide  has 
been  found  there.  A  telluride  of  mercury,  coloradoite,  is  found  with  tel- 
lurides  of  gold  and  silver  and  with  free  gold  in  some  of  the  mines  of  Boulder 
county,  Colo  ,  but  only  in  small  quantities.3  In  notices  of  the  distribu- 
tion of  quicksilver  the  statement  has  often  been  made  that  cinnabar  is  found 
in  Connecticut  in  river  sands.  I  have  not  found  a  citation  of  tlie  original 

O 

authority  for  this  statement.  Prof.  J.  D.  Dana  writes  me  that  he  knows  of 
no  such  occurrence,  and  it  is  safe  to  assume  that  no  discovery  of  cinnabar 
could  have  been  made  near  the  home  of  this  famous  mineralogist  without 
coming  to  his  knowledge. 

Towards  the  beginning  of  the  century  cinnabar  was  reported  at  nu- 
merous points  iu  the  Eastern  States;  it  was  even  said  to  be  very  abundant 
in  the  beach  sands  of  the  Great  Lakes.  Had  these  assertions  been  correct 
they  certainly  would  have  been  confirmed.  Gold  amalgam  has  been  found 
at  Plymouth,  Vt,,  and  the  native  copper  of  one  of  the  mines  at  Lake  Su- 
perior is  said  by  M.  Ilautefeuille  to  contain  a  little  mercury.4 


r.  fur  HITJJ-,  IIiittc.ii-  mill  Salinenwesen  im  preuss.  Staate,  vol.  10,  18(W,  p.  :irfti. 
1  1  ntrlalli  lin-o  mineral!  e  miuiciv,  vol.  1,  183:i,  p.  100. 

'•Kiimioiis  ami  Kcckcr  :  Statistics  and  Technology  of  tbe  Precious  Metals,  Tenth  Census  Repts. 
U.  S.,  vol.  1:5,  p.  iii;. 

4  Geological  Survey  of  Canada,  Otology  of  Canada,  1803,  p.  518. 


16  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Nova  scotia. — In  the  auriferous  region  of  Nova  Scotia  cinnabar  and  native 
quicksilver  are  said  to  have  been  found  at  .Gay's  River  and  globules  of 
the  metal  were  washed  from  a  soft  slate  at  Waverley.1  There  is  certainly 
nothing  improbable  in  these  reports,  for  cinnabar  and  mercury  occur  in 
many  of  the  gold  fields  of  the  world. 

same  Domingo. —  Mr.  W.  S  Courtney2  quotes  "an  English  writer  about 
the  close  of  the  last  century"  as  stating  that  there  is  "mercury  at  the  head 
of  the  river  Yaque."  Mercury  is  also  enumerated  among  the  minerals  of 
Hayti  by  Mr.  J.  D.  Champlin,  jr.3  In  Mr.  Gabb's  memoir  on  Santo  Do- 
mingo I  find  no  mention  of  this  metal. 

Mexico. —  Ores  of  quicksilver  occur  at  a  great  number  of  localities  in 
Mexico,  the  number  of  deposits  being  estimated  by  Prof.  A.  del  Castillo  at 
not  less  than  fifty.  He  is  also  of  the  opinion  that  the  country  is  capable  of 
yielding  annually  the  2,000,000  or  2,500,000  pounds  necessary  for  home 
consumption.4  Most  of  the  mines  appear  to  be  unsatisfactory,  however,  for 
in  1882  but  one  quicksilver  mine  was  in  operation.5 

Quicksilver  ores  occur  in  the  following  States  of  Mexico,  arranged  as 
nearly  as  may  be  in  the  order  of  their  latitude :  Chihuahua,  Durango, 
Zacatecas,  San  Luis  Potosi,  Guanajuato,  Queretaro,  Hidalgo,  Jalisco,  Mex- 
ico, Morelos,  Guerrero,  Oaxuca.  Those  of  Guadalcanal1,  in  the  State  of  San 
Luis  Potosi,  and  of  Huitzuco,  in  the  State  of  Guerrero,  are  the  most  im- 
portant.6 

According  to  Mr.  D.  de  Cortazar7  quicksilver  ores  in  Mexico  occur  in 
primary,  transition,  secondary,  and  tertiary  strata,  but  are  found  every- 
where near  eruptive  rocks. 

Humboldt  describes  one  deposit  as  forming  a  vein  of  considerable  width 
and  length  "in  veritable  pitchstone  porphyry."  The  walls  of  this  vein 
were  impregnated  to  some  extent,  so  that  traces  of  cinnabar  and  metallic 

1  II.  How:   Mineralogy  of  Nova  Scotia,  Hi!1.*,  p   61. 

"The  Gold  Fields  of  St.  Domingo,  1800,  p.  119. 

3Eucyc.  Brit.,  9th  c.d.,  article  Hu.vti. 

4  A  note  communicated  to  tin-  Mining  and  Scientific  Press,  San  Francisco,  January  1G,  1875.  I  re-, 
gret  not  having  liccn  able  to  obtain  a  rojiy  of  this  author's  work,  Momoria  sohru  las  minus  de  azogue 
de  America,  1872. 

6On  the  authority  of  Mr.  Lorenzo  Castro  :  Eucyc.  Brit.,  article  Mexico. 

6S.  Ramirez:  Uiqtiuza  iniucni  de.  Mexico,  p.  91. 

'Repts.  Phila.  luternat.  Exh.  1876  to  Parliament,  vol.  3,  London,  1S78,  p.  389. 


MEXICAN  LOCALITIES.  17 

mercury  were  observed  in  the  porphyry  at  considerable  distances  from  the 
vein.1  At  Durasno,  between  Tierra  Nueva  and  San  Luis  de  la  Paz,  in  the 
State  of  Guanajuato,  he  inspected  a  cinnabar  deposit  forming  a  layer2  rest- 
ing on  porphyry. 

The  cinnabar  deposits  in  the  mining  district  of  Guadalcazar  were  dis- 
covered in  1840.  Though  they  are  numerous  they  appear  to  be  of  no 
great  value,  for  in  1874  they  were  not  yielding  enough  quicksilver  to  sup- 
ply the  demand  in  the  state  in  which  they  lie.3  This  district  forms  the 
subject  of  a  paper  by  Mr.  Ramirez,4  from  which  the  following  notes  are 
taken.  The  country  rock  of  the  district  is  chiefly  limestone,  with  a  few 
intercalated  beds  of  shale.  The  rock  is  compact  and  usually  of  a  bluish- 
gray  tint.  No  fossils  are  known  to  occur  in  it,  nor  does  it  stand  in  such 
relations  to  other  strata  as  to  render  a  stratigraphical  determination  of  its 
age  practicable.  It  is  supposed,  however,  to  be  Cretaceous  both  by  Mr. 
Ramirez  and  by  Mr.  V.  d'Aoust.5  The  region  also  contains  granites  and 
porphyries;  the  latter  inclose  deposits  of  silver  ores,  but  the  quicksilver 
ores  are  confined  to  the  limestone  in  the  district  in  which  this  metal  has 
been  exploited.  According  to  Noggerath,  however,  cinnabar  with  pyrite 
and  galena  is  also  found  in  granite  in  this  region. 

Ores  of  quicksilver  occur  at  numerous  points  along  a  belt  nearly  forty 
miles  in  length  (sixty  kilometers),  which  extends  to  the  northwest  of 
Guadalcazar.  The  deposits  occur  mainly  as  layers  in  the  limestone,  but 

'Essai  politique  sur  le  royaume  de  la  Nouvelle  Espagne,  p.  585.  The  vein  is  called  the  San  Juan 
de  la  Chica.  It  traverses  the  mountain  of  the  Calzoues  and  extends  to  Chichimlara.  I  have  not  been" 
able  to  find  these  localities  on  the  maps. 

2I  shall  use  this  word  to  translate  the  term  man  to,  which  does  not  seem  to  correspond  to  any  ex- 
pression recognized  in  English  or  German  mining  technology  and  seems  also  to  bear  a  somewhat  vari- 
able meaning  among  Spanish-American  miners.  Humboldt  (ibid.,  p.  584)  defines  manto  as  "  une 
couche  horizontale,"  but  hori/.ontality  is  certainly  not  a  necessary  attribute  of  inantos  as  the  term  is 
used  by  Spanish-American  mining  geologists.  Rivero,  in  describing  the  deposits  of  Huancavelica,  re- 
peatedly uses  the  expression  manto  6  capa,  and  capa  is  the  term  employed  for  a  stratum  of  sediment- 
ary rock.  According  to  F.  A.  Moesta  (Ueber  das  Vork.  ;ler  Chlor-,  Rrom-  nnd  lodvorbindnngen,  p.  25), 
the  Chilian  miners  use  this  word  to  describe  any  layer  or  sheet  of  mineral,  irrespective  of  origin,  so 
that  strata  of  sedimentary  rock  and  veins  crossing  strata,  as  well  as  dikes,  may  all  be  called  mantos. 
Rivero,  however,  makes  a  sharp  distinction  between  veins  and  raantos,  and  both  he  and  the  Mexican 
geologists  seem  to  mo  to  understand  by  manto  either  an  ore-bearing  stratum  or  a  deposit  resembling  a 
stratum,  such  as  a  bed-vein,  irrespective  of  the  question  whether  or  not  the  ore  deposition  has  accom- 
panied sedimentation.  No  doubt  the  term  is  much  more  loosely  used  by  miners. 

3  Castillo,  loc.  cit. 

4  Anales  del  ministerio  do  fomento,  Mexico,  vol.  3,  1877,  p.  339. 
"Comptes  rendus  Aead.  sci.,  Paris,  vol.  83,  1876,  p.  289. 

MON  XIII 2 


18  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC!  SLOPE. 

irregular  networks  of  veins,  or  stockworks,  are  also  found.  The  limestone 
forming  the  immediate  walls  of  the  layers  differs  from  that  which  is  more 
remote  from  the  deposits,  the  rock  at  the  contact  tending  to  assume  a 
blackish  color  and  a  compact  granular  structure.  The  deposits  are  ordi- 
narily separated  from  the  country  rock  by  a  deposit  of  gypsum.1  The 
chief  ore  is  cinnabar,  often  hepatic  and  sometimes  accompanied  by  the 
seleno-sulphide  guadalcazarite,  first  described  by  Mr.  del  Castillo  from  this 
locality.  Calcite  and  fluorspar  are  the  gangue  minerals.  Native  sulphur 
occurs  with  the  ore  in  the  principal  vein  of  the  district,  the  Trinidad.  This 
appears  to  me  to  suggest  the  recency  of  the  deposit  and  its  deposition  from 
hot  sulphur  springs;  for  most  native  sulphur  is  certainly  formed  by  the 
decomposition  of  hydrogen  sulphide  in  contact  with  air.  Mr.  Ramirez  sup- 
poses the  sulphur  formed  by  sublimation;  but  I  do  not  find  in  his  descrip- 
tion any  evidence  of  the  former  prevalence  of  very  high  temperatures,  and 
the  presence  of  calcite  and  fluorspar  indicates  deposition  from  solutions. 

The  deposits  of  Huitzuco,  about  fifty  miles  north  of  Tixtla,  in  the 
State  of  Guerrero,  were  discovered  in  March,  1874.  The  geology  and  the 
deposits  of  mercury,  silver,  lead,  and  other  metals  of  this  state  have  been 
described  by  Mr.  T.  L.  Laguerenne.2  Granite  seems  to  underlie  the  coun- 
try. Upon  it  rest  metamorphic  rocks,  including  serpentine  and  eruptive 
masses.  In  the  neighborhood  of  Huitzuco  the  rocks  are  metamorphic  slates 
and  limestones  which  have  been  much  disturbed.  The  cinnabar  deposits 
are  mainly  pockets  of  various  dimensions  and  layers,  but  veins  also  exist. 
The  deposit  of  Tepozonalco  is  a  vein  (veta)  between  slate  and  limestone, 
both  rocks  being  metamorphosed  and  disturbed.  The  ore  is  argentiferous 
and  is  distributed  through  the  entire  vein  matter.  The  ordinary  ore  of  the 
district  is  livingstonite,  a  sulphide  of  antimony  containing  mercury.  Cin- 
nabar is  said  also  to  form  pseudomorphs  after  stibnite.3 

Prof.  F.  Sandberger  has  given  a  very  interesting  account  of  specimens 
of  ore  sent  to  him  from  Huitzuco  by  Mr.  F.  Velten.  They  represent  a  series 
from  fresh  stibnite  to  pseudomorphs  of  cinnabar  after  stibnite,  containing  only 

1 1  suppose  this  mineral  to  result  from  the  reaction  of  iron  sulphate,  produced  by  the  oxidation  ot 
pyrite,  on  the  limrstnnr  walls. 

2AnaIes  del  ministerio  do  fumento,  Mexico,  vol.  7,  1882,  p.  605. 

'Vi-lten  and  Lehnianii:  Siljuin^shrr.  k.  liaj-cr.  Akad.  Wi.su.,  vol.  •>,  Munich,  1HIJ7,  p.  yO'.i,  cited  by 
d'Achiardi, 


SOUTH  AMERICAN  LOCALITIES.  19 

traces  of  antimony.  The  first  step  is  an  oxidation  of  stibnite  to  stibiconite, 
accompanied  by  a  more  or  less  complete  impregnation  with  black,  amorphous 
metacinnabarite.  The  transformation  of  the  whole  mass  to  cinnabar  follows. 
The  change  from  black  to  red  sulphidels~considered  as  due  to  the  probable 
solubility  of  mercuric  sulphide  in  calcium  sulphide.  Quartz  and  gypsum 
are  the  gangue  minerals.1 

At  Chilapa  also,  near  Tixtla,  cinnabar  occurs  in  a  well  defined  vein 
in  metamorphic  slate.  Quartz  and  iron  oxides  constitute  the  gangue,  and 
the  vein  matter  incloses  fragments  of  country  rock.  In  places  the  quartz 
is  stained  with  copper.  Cinnabar  impregnates  the  entire  width  of  the  vein. 
At  San  Onofre  mercurial  ores  occur  under  conditions  similar  to  those 
at  Guadalcazar;  near  San  Felipe  are  veins  of  cinnabar  in  porphyry;  near 
Guanajuato  deposits  of  cinnabar  and  mercuric  iodide  occur  in  Tertiary 
clays  and  conglomerates ;  at  Loma  de  Encinal  veins  of  cinnabar  exist  in 
decomposed  porphyry;  and  rich  mercurial  deposits  are  said  to  occur  at 
Maltrata,  In  1876  Mr.  Geo.  T.  Walker,  reporting  in  manuscript  on  the 
Guanacevi  district,  in  the  State  of  Durango,  calls  attention  to  the  fact  that, 
in  the  La  Colcrada  silver  mine,  ores  containing  cinnabar  occur  close  to  the 
hanging  wall  of  the  vein.  This  occurrence  has  a  parallel  in  this  country 
near  Belmont,  Nev. 

Guatemala. — According  to  Noggerath,  a  specimen  of  cinnabar  from  Gua- 
temala, accompanied  by  barite,  exists  in  Berlin.  I  have  met  with  no  other 
mention  of  quicksilver  ores  in  Central  America. 

SOUTH    AMERICA. 

Colombia. —  Mr.  R.  R.  Hawkins,  of  my  staff,  found  native  quicksilver 
disseminated  in  globules  in  a  clay  soil  near  the  town  of  Graces,  on  the  Isth- 
mus of  Panama.  He  also  found  float  cinnabar  near  the  Magdalena  river, 
in  the  State  of  Tolima.  "  Near  Choco,"  probably  the  bay  of  that  name, 
"  gold  amalgam  and  platinum  are  found  together."2  Humboldt  mentions 
cinnabar  as  occurring  in  the  province  of  Antioqu'ia,  in  the  valley  of  the 
Santa  Rosa,  to  the  east  of  the  river  Cuaca,  and  also  between  the  towns, 
Ibague  and  Carthago. 

1  Sit/uugsber.  k.  bayer.  Akart.  Wiss.,  Munich,  July  3, 1875. 
•  Noggerath,  loc.  cit. 


20 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


Ecuador. — Near  the  town  of  Azogue  (Spanish  for  quicksilver)  cinnabar 
occurs  in  veins  in  the  more  ancient  sandstones.  Between  this  point  and 
Cuenca,  at  which  quicksilver  has  also  been  mined,  fragments  of  cinnabar 
are  found  with  gold  in  gravels.  Deposits  similar  to  those  of  Azogue  are 
worked  within  the  city  of  Loja.1 

Peru. —  Of  late  years  Peru  has  yielded  no  considerable  quantities  of 
quicksilver,  though  it  was  formerly  one  of  the  great  quicksilver-producing 
countries  of  the  world.  The  most  northerly  deposit  is  that  of  Clionta,2  in 
the  western  Andes,  close  to  the  frontier  of  Ecuador.  Mr.  BugdolP  de- 
scribes the  deposit  as  a  bed  in  early  Paleozoic  rocks.  It  is  composed  of 
clay,  sand,  pyrite,  and  cinnabar.  The  ore  impregnates  the  sandstone  foot- 
wall  to  some  extent.  In  the  direction  of  the  strike  the  ore  is  replaced  by 
pyrite.  Veins  of  lead  ore  cross  the  cinnabar  deposit  nearly  at  right  angles. 

In  the  Santa  Apolonia  Mountains,  near  Cajamarca,  globules  of  quick- 
silver occur  in  trachyte.  Specimens  were  exhibited  at  Paris  in  1878  in  the 
fine  collection  of  Mr.  A.  Raimondi.4 

Humboldt  notes  the  appearance  of  quicksilver  at  Vuldivui,  "  in  the 
province  of  Pataz."  There  is  now  no  such  province,  and  I  presume  the 
locality  to  be  near  the  town  of  that  name.  The  same  geologist  states  that 
cinnabar  is  found  at  the  Baths  of  Jesus,  to  the  southeast  of  Guacarachuco 
(probably  another  form  of  the  name  Huacrachuco).  These  baths  are  no 

1  H.  A.  Webster:  Encyc.  Brit.,  article  Ecuador. 

*  The  deposits  mentioned  in  Peru  being  somewhat  nurue'roiis,  the  following  table  may  be  convenient 
to  readers.    The  latitudes  are  only  approximate: 


Localities. 

Provinces. 

Latitude. 

Chonta  

0          1 

Cajamarca  

Pataz  

Libertad  

Huacrachuco.  

Caraz  

Santa  

Huaraz  

Cerro  de  Pasco  

Tauli  

Huancavelica  

Ayaviri  

14    40 

3Zeitschr.  fiir  Berg-,  Hiitten-  uitd  Salinenwesi'ii  im  prc.iias.  Staatr,  vol.  10, 1802,  p.  3'J1. 
<G.  vom  Rath:  Naturwiss.  Stndien,  Bonn,  1879,  p.  \rci. 


IIUANOAVELICA.  21 

doubt  hot  springs.  He  also  mentions  this  ore  at  Guaraz  (Huaraz)  and  near 
Santa. 

In  the  province  of  Ancachs1  mercury  occurs  in  only  a  few  deposits, 
which  appear  to  be  of  little  value.  Itris-always  found  as  cinnabar  in  veins, 
and  mixed  with  other  sulphides,  such  as  galena,  blende,  pyrite,  and  gray 
copper.  One  of  the  principal  mines  is  the  Santa  Cruz,  near  Caraz.  The 
large  amount  of  carbonic  anhydride  evolved  in  this  mine  renders  its  ex- 
ploitation difficult. 

There  is  a  quicksilver  mine  in  the  great  silver-mining  district  of  Cerro 
de  Pasco,  at  Cuipan.  The  rocks  of  this  region  include  granite  and  trachytic 
lavas,  as  well  as  more  or  less  metamorphosed  sedimentary  beds.^ 

In  the  mineral  district  of  Yauli,  75  miles  northeast  of  Lima,  close  to 
the  Punabamba  ranch,  in  a  valley  of  the  Andes,  hot  sulphur  springs  reach 
the  surface  and  deposit  considerable  quantities  of  sulphur.  Above  these 
springs  are  quartz  veins  carrying  seams  and  pockets  of  cinnabar  and  pyrite. 
The  inclosing  rocks  are  schists  and  sandstones.3 

For  over  two  hundred  years  the  district  of  Huancavelica  (sometimes 
written  Guancavelica)  yielded  almost  as  much,  possibly  quite  as  much, 
metal  as  the  district  of  Almaden,  and  the  recorded  total  product  of  Huan- 
cavelica considerably  exceeds  that  of  California.  The  district  of  Huanca- 
velica lies  on  the  eastern  slope  of  the  western  range  of  the  Cordilleras.  The 
rocks,  according  to  Mr.  Crosnier,4  are  of  Jurassic  age  and  are  elevated  to  a 
nearly  vertical  position,  but  have  a  westerly  dip.  They  strike  north  and 
south.  The  sedimentary  rocks  are  the  same  throughout  the  district,  and 
consist  of  argillaceous  schists,  conglomerates,  sandstone,  and  limestone, 
alternating  in  thick  beds.  There  are  also,  according  to  Mr.  Rivero,5  por- 
phyries and  trachytic  lavas  in  the  district,  and  granite  is  exposed  at  least  at 
one  locality.  All  traces  of  volcanic  action  have  not  disappeared  from  this 

'Explotacion  y  beneficio  de  los  miuerales  de  Ancachs,  Prof.  M.  du  Chatenet:  Auales  constr.  civ. 
y  ininas  1'ern,  vol.  Ii,  1883,  p.  :!. 

3Alijandro  Babiuski,  State  engineer:  Informe  sobre  el  Cerro  de  Pasco,  1876. 

"Bngdoll,  loc.  cit. ;  Mineral  de  Yauli,  por  L.  Pfliicker  y  Rico:  Anales  constr.  civ.  y  rainas  Peru,  vol. 
3,  1883,  p.  62. 

'Annales  des  mines,  Paris,  5th  series,  vol.  2,  1852,  p.  37. 

6Memoria  sobre  el  rico  mineral  de  azogue  de  Huancavelica,  por  Mariano  Eduardo  de  Rivero, 
Lima,  1848. 


22  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

region.  In  the  environs  of  the  town  are  hot  springs  still  depositing  sinter, 
and  so  abundant  is  this  material  that  the  town  is  built  of  it.  The  most 
famous  mine  is  the  Santa  Barbara,  close  to  the  town  of  Huancavelica,  but 
there  are  over  forty  points  at  which  cinnabar  occurs,  the  most  remote  being 
18  leagues  (20  to  a  degree)  from  the  Santa  Barbara,  and  sixteen  of  them 
within  2  leagues.  The  department  of  Huancavelica  contains  silver,  copper, 
lead,  iron,  and  coal,  as  well  as  quicksilver. 

The  deposit  of  Santa  Barbara  consists  of  impregnations  of  cinnabar, 
mainly  in  sandstone.  Some  observers  have  pronounced  it  a  vein,  but  Mr. 
Rivero  denies  that  this  name  is  applicable  and  considers  it  a  layer  or  bed 
running  parallel  with  the  beds  of  limestone,  sandstone,  and  conglomerate. 
Humboldt  points  out  that  cinnabar  occurs  close  to  Huancavelica  in  two  very 
different  ways,  in  part  in  true  veins  (filons)  and  in  part  in  strata  (couches). 
In  the  Santa  Barbara  it  occurs  chiefly  as  impregnations  in  portions  of  the 
sandstone  bed,  though  much  of  the  sandstone  is  barren;  but  he  states  that 
in  portions  of  the  deposit  the  cinnabar  forms  stringers,  which  are  sometimes 
reticulated,  forming  a  true  stockwork  or  irregular  reticulated  mass.  Ac- 
cording to  Crosnier  profound  disturbance  of  the  rocks  preceded  the  deposi- 
tion of  ore,  and  the  deposit  appears  to  me  therefore  to  be  a  tabular  impreg- 
nation intimately  related  to  a  fissure  system.  The  difference  between  such 
a  deposit  and  a  bed  vein  does  not  seem  great  or  important.  Besides  pyrite 
the  mine  carries  much  mispickel  and  realgar,  differing  in  this  respect  from 
the  other  great  cinnabar  deposits  of  the  world,  though  similar  associations 
in  smaller  deposits  are  frequent.  According  to  Humboldt  the  arsenic  is 
found  almost  exclusively  in  the  lower  levels.  He  also  mentions  galena 
among  the  metallic  minerals.  Calcite  and  barite  are  the  gangue  minerals. 

The  Santa  Barbara  was  discovered  in  1566  by  Enrique  Garcc's,  but  it 
had  long  been  known  to  the  Indians,  who  called  cinnabar  llimpi  and  used  it 
to  paint  their  bodies.  According  to  Mr.  Rivero  no  historian  has  mentioned 
that  they  obtained  quicksilver  by  the  distillation  of  cinnabar.  He  states, 
however,  that  in  the  immediate  neighborhood  of  the  Santa  Barbara  there 
are  remains  of  ancient,  very  small,  retort-shaped  furnaces  in  which  the  sub- 
jects of  the  Peruvian  Incas  reduced  cinnabar.  In  this  connection  it  is 
interesting  to  note  that  in  the  northern  part  of  Chili,  according  to  Mr.  V. 


SOUTH  AMERICAN  LOCALITIES.  23 

Perez-Kosales,1  the  Indians  of  the  present  day  extract  quicksilver  from  cin- 
nabar in  small,  rudely  made,  earthen  retorts  (cornues  en  terre)  and  supply 
the  demand  of  the  gold  mines  of  the  region.  Has  this  industry  survived 
among  the  natives  from  the  time  of  the  Ineas?  It  might  also  be  asked  what 
connection,  if  any,  existed  between  the  primitive  furnaces  of  the  Indians 
and  the  aludels  of  the  Bustamente  furnace  which  was  invented  at  Huanca- 
velica  in  1G33  by  Lope  Saavedra  Barba,  a  physician  and  prospector. 

Native  quicksilvei  is  found  in  the  pores  of  a  trachyte  at  Ayaviri,  de- 
partment of  Puno,2  and  this  is  the  most  southerly  locality  in  Peru  of  which 
I  have  notes. 

Bolivia.  —  It  is  stated  that  cinnabar  is  among  the  ores  of  Bolivia  and 
that  quicksilver  is  frequently  found  associated  witli  silver  ores.3 

chiH.  —  Mr.  Crosnier,  in  discussing  the  deposits  of  Chili  and  Peru  (loc. 
cit.),  remarks  that  deposits  of  mercury  appear  to  occur  indifferently  in 
stratified  rocks  and  in  granite.  The  Punita  mine,  in  Chili,  is  in  the  latter. 
According  to  Mr.  Rosales  (loc.  cit.)  cinnabar  occurs  in  the  northern  prov- 
inces, especially  near  Andacollo,  in  the  province  of  Coquimbo.  Near  the 
town  of  Chili4  cinnabar  is  found  in  dendritic  forms,  inclosed  in  quartz. 
Amalgams  are  well  known  to  be  frequent  in  the  Chilian  precious  metal 
mines,  especially  at  Arqueras. 

The  Argentine  Republic.  —  It  has  been  asserted  that  traces  of  mercury  have 
been  found  in  the  sandstones  at  La  Cruz  and  at  Santo  Tome".  Professor 
Stelzner5  regards  this  occurrence  as  extremely  problematical.  These  local- 
ities lie  in  the  northeastern  part  of  the  republic.  The  northwestern  corner 
of  the  country,  adjoining  portions  of  Peru  and  Chili  known  to  contain  mer- 
curial ores,  does  not  appear  to  have  been  explored  to  any  considerable 
extent. 

Brazil.  —  There  is  no  doubt  that  quicksilver  occurs  in  southern  Brazil, 
but  the  information  concerning  it  is  very  indefinite  and  probably  in  part 
erroneous.  In  1865  Dr.  Bosquet,  a  resident  of  Paranagua,  stated  that  at 

1  Essai  sur  le  Chili,  1857,  p.  166. 

2G.  vom  Rath,  loc.  cit.     In  view  of  the  investigations  of  later  years  on  the  supposed  trachytes  of 
the  Pacific  Slope,  it  is  not  improbable  that  the  two  mercurial  lavas  of  Peru  are  really  andesites. 
3J.  A.  Phillips:  Ore  Deposits,  p.  GiO  ;   Keith  Johnston  :  Encyc.  Brit.,  article  Bolivia. 
4Xoj;gerath,  loc.  cit.     I  cannot  find  such  a  town  on  the  maps. 
6Gool.  uml  Pal.  Arg.  Rop.,  1885,  p.  249. 


Of 

TJUI7ERSIT7 


24  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

one  of  the  extremities  of  the  city  a  deposit  of  mercury  existed  so  abundant 
that  in  the  rainy  season  it  flowed  from  a  talus  on  the  borders  of  the  sea.1 
Mr.  G.  C.  Broadhead  states  that  mercury  is  found  in  rich  quantities  in  the 
province  of  Parana,  and  is  also  found  in  Santa  Catherine  and,  in  the  metallic 
state,  in  Sao  Paulo.2  In  1886  Mr.  J.  C.  Gomes,  of  the  Brazilian  legation 
at  Washington,  wrote:  "Mercury  has  been  discovered  at  the  Capao  d'Anta, 
in  the  province  of  Parana,  in  quantities  that  will  permit  competition  with 
mines  of  Europe,  Peru,  and  California"3  Prof.  Orville  Derby,  of  whom 
I  made  inquiry,  writes  me  that  the  only  authoritative  reference  known  to 
him  is  by  W.  L.  von  Eschwege.4  Cinnabar,  according  to  this  geolo- 
gist, occurs  sparingly  in  rounded  grains  in  gold  sands  in  the  bed  of  a  stream 
flowing  from  the  itacolumite  mountain  of  Cachoeira,  near  Ouro  Preto 
(formerly  Villa  Rica).  It  is  not  known  that  this  locality  has  been  re- 
examined.  Professor  Derby  has  visited  two  localities  at  which  it  is  said 
that  native  mercury  was  found,  but  could  detect  none  and  is  inclined  to 
suspect  an  artificial  origin.5  He  is  of  the  opinion  that  the  Capao  d'Anta 
locality  requires  further  investigation.  The  neighboring  region  is  one  of 
undisturbed  Devonian  shales  and  sandstones.  The  occurrence  was  reported 
by  Mr.  Keller,  who  visited  it  in  1864  or  1865,  to  be  native  quicksilver  found 
in  loose  earth  in  a  gully,  and,  so  far  as  Professor  Derby  knows,  only  a  few 
ounces  have  been  collected  as  a  curiosity. 

ICELAND. 

The  Great  Geyser. — During  his  well-known  investigation  of  the  Great  Gey- 
ser, Mr.  Des  Cloizeaux  found  metallic  mercury  and  mercuric  sulphide  in 
the  geyserite  of  which  the  basin  of  that  remarkable  spring  is  composed. 
At  the  time  of  this  examination  similar  occurrences  elsewhere  were  un- 
known or  had  been  very  imperfectly  studied,  and  the  probability  that  the 
presence  of  the  metal  was  due  to  artificial  transportation  seemed  so  great 

1  Bull.  Soc.  geographic,  Paris,  5th  series,  vol.  9,  1865,  p.  528. 

»Rept.  Phila.  Internal.  Exh.  187G  to  Parliament,  vol.  3,  London,  1878,  p.  494. 

3 Commercial  and  Emigrational  Guide  to  Brazil,  Compiled  and  Translated  from  Official  Publica- 
tions, Washington,  1886. 

4  Beitriigo  zur  Gebirgskunde  Brasiliens,  1832,  p.  283. 

"The  localities  are  the  island  of  Itaparica,  in  front  of  the  city  of  Bahia,  and  the  fageuda  de  Bon 
Successo,  on  the  Rio  das  Velliaa,  mentioned  by  R.  F.  Burton  (The  Highlands  of  Brazil,  vol.  2, 1869,  p.  69). 


THE  GREAT  GEYSER.  25 

as  to  deter  Mr.  Des  Cloizeaux  from  mentioning  the  discovery  in  his  memoir 
on  the  Great  Geyser.1  He  collected  numerous  specimens,  however,  some 
of  which  he  was  kind  enough  to  show  me,  and  noted  the  conditions  in 
detail.  During  the  last  forty  years  quicksilver  and  its  sulphides  have  re- 
peatedly been  discovered  in  close  relations  to  thermal  springs,  and  it  no 
longer  seems  intrinsically  improbable  that  this  occurrence  was  produced  by 
deposition  from  natural  solutions.  Indeed,  it  has  repeatedly  been  referred 
to  in  the  later  literature,  though  not  by  its  discoverer,  as  if  it  were  beyond 
question  a  natural  deposit. 

The  basin  of  the  Great  Geyser  is  about  eighteen  meters  in  diameter, 
and  the  point  at  which  the  quicksilver  was  found  is  within  the  rim  exactly 
due  east,  magnetic,  from  the  vent.  Traces  of  the  metal  were  detected  over 
an  area  of  about  one  square  meter,  and  Mr.  Des  Cloizeaux  roughly  esti- 
mates the  entire  quantity  of  mercury  which  he  collected  at  about  half  a 
pound.  It  occurred  at  depths  from  the  surface  of  the  sinter  varying  from 
one  or  two  millimeters  to  about  four  centimeters.  The  specimens  which  I 
saw  seem  to  show  that  the  mercury  was  originally  deposited  in  the  me- 
tallic state,  for  liquid  globules  of  the  metal  about  two  millimeters  or  less  in 
diameter  are  often  partially  enveloped  in  crusts  of  black  sulphide,  mani- 
festly produced  by  the  action  of  soluble  sulphides  on  the  inclosed  metallic 
drops.  Portions  of  the  sinter,  at  some  distance  from  visible  globules  of 
quicksilver,  were  stained  black  by  mercuric  sulphide,  and  at  some  points 
small  quantities  of  the  red  sulphide  made  their  appearance. 

The  fact  tljat  cinnabar  accompanies  this  quicksilver  shows  that  the 
water  of  the  geyser  is  capable  of  dissolving  traces  of  mercuric  sulphide;  for, 
had  not  this  been  the  case,  only  metacinnabarite  could  have  resulted  from 
the  attack  of  metallic  mercury  by  soluble  sulphides.  The  investigations 
described  in  Chapter  XV  of  this  memoir  also  show  that  mercuric  sulphide 
is  soluble  to  a  considerable  extent  in  waters  of  a  composition  similar  to  that 
of  this  great  spring.  Such  solubility  is  evidently  a  necessary  condition  of 
the  hypothesis  that  the  mercury  was  deposited  from  the  water. 

On  the  other  hand,  there  are  circumstances  connected  with  the  occur- 
rence which  seem  to  me  to  point  somewhat  strongly  to  an  artificial  origin. 

1  Annales  do  cliimie,  Paris,  vol.  19,  1847,  p.  444.     The  information  given  in  the  text  was  verbally 
communicated  to  me  by  Mr.  Des  Cloizeaux. 


26  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Judging  from  the  specimens,  it  would  appear,  as  already  mentioned,  that 
nearly  or  quite  all  of  the  quicksilver  was  originally  deposited  in  the  metallic 
state  and  that  the  sulphide  accompanying  it  is  of  secondary  origin.  Now, 
though  more  or  less  native  quicksilver  often  accompanies  deposits  of  cinna- 
bar, the  metallic  mercury  usually  forms  biit  a  small  proportion  of  the  entire 
ore.  To  this  rule  there  are  some  exceptions.  At  the  Rattlesnake  mine,  in 
California,  for  example,  a  large  part  of  the  quicksilver  was  native,  but  here, 
and  at  other  points  in  the  same  State  at  which  native  quicksilver  was  abun- 
dant, it  was  also  accompanied  by  unusual  quantities  of  bituminous  oils,  which 
were  probably  not  without  effect  upon  the  form  in  which  the  metal  was 
deposited.  Near  Montpellier,  France,  also,  quicksilver  has  been  found  in 
some  quantity,  so  far  as  I  know  unaccompanied  by  cinnabar.  But  the  depo- 
sition of  quicksilver,  almost  exclusively  in  the  metallic  state,  from  waters  such 
as  that  of  the  Great  Geyser,  containing  soluble  sulphides  and  little  or  no  or- 
ganic matter,  is  very  hard  to  understand.  It  is  also  very  difficult  to  account 
for  the  distribution  of  the  metal  on  the  supposition  that  it  was  brought  to  the 
surface  in  solution  by  the  heated  waters.  The  basin  of  the  Great  Geyser 
is  extremely  symmetrical;  in  other  words,  the  deposition  of  mineral  matter 
takes  place  with  great  uniformity  on  all  sides  of  the  vent.  Now,  although 
the  quantity  of  quicksilver  found  Avas  by  no  means  inconsiderable  at  a 
single  spot,  it  was  detected  nowhere  else  in  the  basin.  It  seems  highly 
improbable  that  the  metal  should  have  been  deposited  from  the  water 
without  any  approach  to  symmetry  of  distribution.  In  the  opinion  of  Mr. 
Des  Cloizeaux,  it  is  not  difficult  to  imagine  circumstances  under  which  a 
barometer  might  have  been  broken  at  the  point  where  the  mercury  was 
found.  The  water  sinks  periodically  into  the  vent,  leaving  the  point  in 
question  bare,  and  returns  again  with  a  rush.  An  observer,  taking  the  op- 
portunity to  advance  as  close  to  the  vent  as  possible,  would  have  to  fly  for 
his  life  as  the  water  returned,  and  might  well  drop  his  instruments. 

Professor  Bunsen,  who,  as  is  well  known,  was  engaged  in  investigating 
the  geysers  at  the  same  time  with  Mr.  Des  Cloizeaux,  also  examined  this 
occurrence  of  quicksilver,  and  has  informed  me  that  in  his  opinion  it  was 
certainly  the  result  of  an  accident  and  was  not  a  natural  deposit, 


SPANISH  LOCALITIES.  27 

^ 

EUROPE. 

Northwestern  Europe. — Amalgams  have  been  found  at  Kongsberg,  in  Nor- 
way,1 and  at  Sala,  in  Sweden,2  but  no  cinnabar  has  been  discovered  in 
Scandinavia,  so  far  as  I  am  aware.  In  the  Scotch  highlands,  Black3  re- 
ported an  ore  containing  lead,  copper,  and  a  little  silver,  which,  on  distilla- 
tion, yielded  some  mercury.  Possibly  this  may  have  been  a  tetrahedrite. 
According  to  Prof.  R.  Jameson,  a  quantity  of  quicksilver  was  found  in  a 
peat  moss  on  the  Scotch  island  of  Isla  about  the  beginning  of  this  century. 
Some  further  search  was  made  with  no  result.4  I  should  regard  such  an 
occurrence  as  almost  certainly  due  to  human  agency. 

Portugal. —  A  quicksilver  mine  is  said  to  have  existed  in  the  latter  part 
of  the  last  century  in  gravels.  The  locality  seems  to  be  at  Conna,  on  the 
Tagus,  not  far  from  Lisbon.5 

spam. —  Near  Mieres,6  to  the  south  of  Oviedo,  in  Asturia,  cinnabar 
deposits,  which  had  been  worked  long  ago,  and  probably  by  the  Romans, 
were  rediscovered  soon  after  1840.  The  country  rock  in  this  district  is 
composed  of  carboniferous  sandstones  and  schists.  The  crest  of  a  range 
of  hills  is  formed  of  a  breccia,  bounded  on  both  sides  by  broken  and  con- 
torted beds  of  sandstone  and  schist,  and  composed  of  fragments  of  these 
rocks.  In  this  breccia,  or  belt  of  extreme  disturbance,  occur  cinnabar, 
pyrite,  mispickel,  and  realgar.  The  ore  is  thus  similar  to  that  of  Huan- 
cavelica.  The  cinnabar  fills  cracks  and  interstitial  cavities  and  sometimes 
appears  as  impregnations  Some  streaks  of  ore  are  four  to  six  inches  in 
width.  My  authority  speaks  of  no  gangue  mineral,  but  mentions  a  deposit 
of  ferrous  carbonate  in  one  portion  of  the  belt  with  the  cinnabar,  and,  so 
far  as  gangue  minerals  are  present,  they  are  perhaps  carbonates.  The 
ore-bearing  belt  is  forty-five  to  sixty-five  feet  wide  and  about  four  miles 
in  length.  It  seems  manifest,  as  Mr.  Klemm  concludes,  lhat  these  deposits 

1  Reports  of  tile  American  Commissioners  on  the  Paris  Exposition  of  1878,  Mining  Industries,  by 
J.  D.  Hague,  vol.  4,  p.  270. 

2  A.  Noggerath,  loc.  cit. 

3Niiggerath,  loc.  cit.,  probably  Joseph  Black,  who  wrote  various  treatises  towards  the  close  of  tho 
last  century. 

4  Mineralogical  Travels  etc.,  vol.  1,  1813,  p.  153. 

5  V.  d'Aoust,  Comptes  rendus  Acad.  sci.,  Paris,  vol.  83, 1876,  p.  289,  and  Noggerath,  loc.  cit. 

6  J.  G.  Klemm  :  Berg-  untl  hiittenm.  Zeitung,  vol.  26,  1867,  p.  13. 


28  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

are  more  recent  than  the  shattering  of  the  mass  in  which  they  occur.  At 
Santander,  in  the  same  province,  cinnabar  forms  pockets  in  the  lead  and 
zinc  ores.1  Casiano  de  Prado  mentions  the  occurrence  of  cinnabar  and 
coal  together  from  this  province,  the  coal  being  unaltered. 

The  mines  of  Almaden  are  not  only  the  greatest  quicksilver  mines  in 
the  world,  but  have  yielded  a  product  exceeded  in  value  by  very  few  mines 
of  any  kind.2  The  name  given  by  the  Moors  (al  maden,  the  mine)  was 
therefore  not  inappropriate.  Cinnabar  from  Spain  is  frequently  mentioned 
by  the  ancient  writers,  and  the  indications  are  that  it  came  from  this  locality. 
The  accounts  reach  back  to  415  B.  C.,  when  an  Athenian,  Callias  by  name, 
is  said  to  have  invented  and  made  known  a  method  of  separating  cinnabar 
from  earthy  matter  and  to  have  acquired  a  fortune  by  mining  in  Spain. 
Pliny  describes  the  locality  under  the  name  of  Sisapo  in  such  a  way  as  to 
leave  no  doubt  that  the  mining  district  of  Almaden  is  meant.  A  few  tons 
of  cinnabar  were  extracted  yearly  by  the  Romans  for  use  as  pigment.  The 
mines  were  certainly  worked  by  the  Moors,  but  no  details  are  now  extant. 
Work  on  a  considerable  scale,  so  far  as  is  known,  was  first  initiated  by  the 
German  bankers,  the  brothers  Fugger,  to  whom  the  mines  were  farmed  in 
1525  and  who  retained  control  till  1645.  The  demand  for  quicksilver  did 
not  in  fact  reach  large  proportions  until  the  discovery  of  the  process  of 
extracting  silver  from  its  ores  with  the  help  of  mercury  by  Bartolome  de 
Mddina,  a  Mexican  miner,  in  1557.  Work  seems  to  have  been  prosecuted 
from  the  earliest  times  on  portions  of  the  deposits  which  are  still  being  ex- 
ploited. Various  other  deposits  within  a  distance  of  ten  miles  have  been 

1  G.  Dewalque :  Revue  de  g<5ologie  pour  les  amides  1864  et  18G5,  vol.  4,  Paris,  1806,  p.  94. 

2  The  priucipal  authority  ou  the   geology  of  the  Almaden  mine  is  Casiano  de  Prado,  Bull   Soc. 
g6ologiqne  France,  2d  series,  vol.  12,  1835.     The  paleontological  portiou  of  this  memoir  is  by  Messrs,  de 
Verneuil  aud  Barraude.     All  subsequent  writers  owe  much  to  this  important  work.     Valuable  pa- 
pers have  also  been  published  by  the  following  geologists  and  engineers:    Bernaldez  and  Figueroa 
(Memoria  sobre  las  miuas  do  Almaden  y  Aliuadenejos,  Madrid);  A.  Noggerath  (Zeitschr.  fiir  Berg-, 
Hiitten-  und  Salineuwesen  im  preuss.  Staate,  vol.  10,  1832,  p.  361) ;  Jos6  de  Monasterio  y  Correa  (Rev. 
univ.  mines,  vol.  29,  1871,  p.  1) ;  II.  Kuss  (Annales  des  mines,  Paris,  vol.  13,  1878,  p.  39) ;  and  Caron 
(Zeitschr.  fiir  Berg-,  Hiitteu-  und  Salinenwesen  im  preuss.  Staate,  vol.  28,  1880,  p.  126).     More  general 
is  M.  D.  de  Cortazar's  Reseua  fisico-geologica  de  la  provincia  de  Ciudad  Real.    Prof.  R.  Helmhacker  has 
investigated  the  diabase  and  piedra  frailesca  of  Almadeu  in  Tschermaks  mineralogische  und  petro- 
graphische  Mittheilungen,  1877,  and  Prof.  Salvador  Calderon  has  studied  the  massive  rocks  of  the  dis- 
trict (Anales  Soc.  espan.  hist,  nat.,  vol.  13,  1884,  p.  227). 

The  account  of  Almadeu  given  in  the  text  was  compiled  before  my  visit  to  the  spot,  and  I  have 
added  to  it  only  one  or  two  observations  which  seemed  necessary  to  obviate  misunderstandings.  My 
own  results  will  appear  separately. 


ALMADEN.  29 

discovered  from  time  to  time,  but  are  said  now  to  be  exhausted  or  abandoned 
for  other  reasons. 

The  prevailing  rocks  of  the  Almadeu  district  are  schists,  quartzites, 
and  sandstones,  together  with  small  quantities  of  limestone,  all  of  Silurian 
and  Devonian  age.  Intimately  associated  with  the  deposits,  though  seldom 
in  direct  contact  with  the  ores,  is  a  rock  called  piedra  frailesca.  According 
to  de  Prado  this  is  a  metamorphosed  breccia,  consisting  of  grains  of  quartz, 
calcium  carbonate,  dolomite,  and  fragments  of  schist  cemented  by  dolomitic 
c'alcite.  It  occurs  in  lenticular  masses  intercalated  in  the  schists  and  has 
been  found  to  contain  Silurian  fossils.  Messrs.  Helmhacker  and  Calderon 
regard  the  rock  as  a  diabase  tufa.  Cracks  in  this  rock  sometimes  carry 
cinnabar,  the  deposition  of  which  is  therefore  later  than  the  brecciation. 

The  district  lies  upon  the  northern  flank  of  the  Sierra  Morena.  In 
this  range  are  extensive  areas  of  granite,  and  a  rock  also  called  granite 
crops  out  at  various  points  not  many  miles  to  the  north  of  the  mines.  Di- 
abase, or  melaphyre,  has  broken  through  the  sedimentary  rocks  and  occu- 
pies considerable  areas  near  the  mine,  and  a  small  quantity  of  porphyry, 
regarded  as  trachytic  by  de  Prado,  but  as  Pre-Tertiary  by  more  recent  Span- 
ish geologists,  exists  some  six  miles  northeast  of  Almaden.  The  sediment- 
ary rocks  are  nearly  vertical  and  are  said  to  be  little  disturbed  by  the 
diabase  eruptions,  which  have  naturally  reached  the  surface  along  the 
planes  of  bedding.  The  strata  carry  enough  fossils  for  a  satisfactory  de- 
termination of  the  age  of  the  rocks  as  a  whole,  but  the  same  beds  seem  to 
reappear  more  than  once  in  the  compressed  folds,  and  it  is  often  difficult  to 
decide  to  which  of  the  periods  a  particular  stratum  belongs. 

The  Almaden  district  contains  many  deposits  of  cinnabar  scattered 
over  an  area  of  about  ten  miles  by  six,  but  neither  these  nor  the  ranges  of 
hills  exactly  follow  the  strike  of  the  strata,  which  is  very  closely  east  and 
west.  There  seems  to  be  some  tendency,  however,  both  with  the  deposits 
and  the  ranges,  to  arrangement  in  the  same  direction. 

The  chief  ore  is  of  course  cinnabar,  accompanied  by  relatively  small 
quantities  of  metallic  mercury.  Pyrite  occurs  in  small  quantities,  and 
Caron  detected  chalcopyrite.  Gangue  minerals  have  been  said  to  be  al- 
most entirely  wanting,  but  Noggerath  detected  a  little  heavy  spar  with  the 


30  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

ore,  and  spots  of  bituminous  matter  are  sometimes  found.  I  found  quartz 
gangue  abundant  both  in  the  reserves  and  in  the  newer  exposures. 

The  deposits  of  the  Almaden  mine  consist  of  three  tabular  masses  of 
ore,  nearly  600  feet  long  and  from  12  to  25  feet  in  thickness.  They  stand 
almost  vertically  and  nearly  coincide  in  position  with  the  surfaces  of  strat- 
ification. The  southernmost  body  is  called  San  Pedro  y  San  Diego ;  then 
come  the  San  Francisco  and,  still  farther  to  the  north,  the  San  Nicolas. 
The  first  of  the  three  consists  of  a  stratum  of  sandstone  (or  quartzite,  as  it  is 
called  by  some  authors)  impregnated  to  a  large  extent  with  cinnabar.  The 
impregnation  differs  in  degree  and  is  sometimes  so  complete  that  de  Prado 
infers  a  partial  replacement  of  the  material  of  the  rock  by  the  metallic  sul- 
phide. Most  later  writers  have  accepted  de  Prado's  view,  but  I  could  find 
no  evidence  to  sustain  it.  In  the  two  more  northerly  bodies  the  deposits 
consist  of  quartzite  intersected  by  stringers  and  seams  of  cinnabar.  The 
seams  are  sometimes  parallel  to  one  another  and  sometimes  intersect  the 
rock  in  every  direction.  Occasionally  portions  of  the  quartzite  appear  to 
be  impregnated  with  cinnabar.  The  walls  of  the  deposits  are  formed  by 
quartzite  and  slate.  When  quartzite  is  the  wall  rock  the  ore  dies  out  into 
it  gradually,  but  scarcely  a  trace  is  to  be  found  in  the  slate.  Diabase  in  a 
highly  decomposed  condition  is  said  to  cut  off  the  San  Nicolas  and  the  San 
Francisco  to  the  east. 

The  ore  does  not  always  follow  a  single  stratum,  but,  according  to 
Kuss,  sometimes  passes  abruptly  from  one  stratum  to  another.  Slicken- 
sides  are  noted  in  the  schists  by  Caron,  who  also  mentions  small  faults  in 
the  San  Nicolas,  which  did  not  reappear  in  the  San  Francisco. 

There  has  been  much  difference  of  opinion  as  to  the  classification  of 
these  deposits.  Early  authors  regarded  them  as  veins  ;  de  Prado,  who  con- 
sidered that  the  ore  was  introduced  from  below  after  the  formation  of  the 
beds,  regarded  the  deposits  as  ore-bearing  strata,  but  not  as  veins.  Nog- 
gerath  assents' to  this  opinion,  pointing  out  that  many  phenomena  common 
in  veins  are  not  found  here.  Caron  calls  them  impregnations  and  denies 
that  they  are  veins  or  beds.  Kuss  says:  "So  soon  as  one  admits,  with  Mr. 
de  Prado,  that  the  mercury  is  derived  from  the  earth's  interior,  so  soon  as 
one  recognizes  that  the  deposits  of  Almaden  form  relatively  narrow  belts, 


SPANISH  LOCALITIES  ^».          or      -  V/      31 

following  a  single  direction  and  having  a  determinate~dTp,  we  do  not  see 
how  one  can  refuse  them  the  name  of  veins."  For  my  part  I  am  not  aware 
that  any  definition  of  vein  has  been  proposed  which  would  exclude  the  San 
Francisco  and  the  San  Nicolas  as  they  are  described,  nor  can  I  see  how  a 
definition  could  be  given  which  would  exclude  these  bodies  without  also 
excluding  the  greater  portion  of  known  veins.  The  San  Pedro  y  San  Diego 
would  also  seem  from  the  descriptions  to  be  a  vein-like  impregnation,  differ- 
ing from  the  others  chiefly  in  the  size  of  the  interstitial  cavities,  which,  for 
the  most  part,  the  cinnabar  has  filled. 

It  is  a  very  remarkable  fact  that  the  Almaden  mine  appears  to  grow 
richer  as  the  depth  increases.  No  other  known  quicksilver  deposit  exhibits 
this  valuable  peculiarity  excepting  the  Idria.  It  is  also  interesting  to  note 
that  the  other  deposits  of  the  Almaden  district  have  given  out  in  depth, 
though  they  occupied  a  similar  position  in  the  same  rocks.  The  relations 
of  cinnabar  deposition  to  depth  are  thus  evidently  determined  by  purely 
local  causes,  and  not  by  any  general  principle  governing  precipitation. 
Hence  it  is  quite  possible  that  deposits  which  grow  stronger  as  distance  from 
the  surface  increases  may  be  found  in  any  quicksilver  district  Monasterio 
and  Kuss  believe  the  deposition  of  ore  and  the  eruption  of  the  diabase  to 
be  closely  related. 

The  province  of  Granada  also  contains  quicksilver  along  the  southern 
base  of  the  Sierra  Nevada.  That  range  is  composed  of  micaceous  and 
chloritic  schists  and  serpentine.  The  central  mass  contains  little  ore  of 
any  kind,  but  gold,  lead, "copper,  zinc,  cobalt,  and  nickel  ores  are  found 
along  its  edges.  The  quicksilver  belt  has  been  traced  from  Torbiscon,  in 
Granada,  to  Purchena,  in  Almeria,  and  runs  on  a  somewhat  more  northerly 
course  than  the  Sierra.  This  strip  of  country  contains  numerous  veins  of 
cinnabar  in  talcose  schists  of  Triassic  age.  The  mercurial  ore  is  accom- 
panied by  gray  copper,  sulphides  of  nickel  and  cobalt,  and  oxides  of  iron. 
The  veins  are  small  and  irregular.  In  the  soft  rocks  there  is  a  tendency  to 
the  diffusion  of  ore.1 

Mr.  A.  Heckmanns,  a  mining  engineer  of  large  experience  in  the 
mineral  districts  of  Spain  and  Algeria,  informs  me  that  a  distinct  vein 

1  Guillemiu-Tarayrc,  Comptes  remlus  Acad.  sci.,  Paris,  vol.  100,  r8-C>,  p.  1231. 


32  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

carrying  cinnabar  exists  in  slates  supposed  to  be  Silurian  in  the  Sierra  de 
Montenegro,  which  is  the  eastern  end  of  the  great  Sierra  Nevada.  Cin- 
nabar and  silver  amalgam,  containing  G  per  cent,  of  quicksilver,  perhaps 
kongsbergite,  occur  near  Culvas  de  Vera,  in  the  province  of  Almeria. 
Copper  and  lead  ores  occur  in  the  same  neighborhood.  At  Aquilas,  on  the 
boundary  between  Murcia  and  Almeria,  quicksilver  ore  was  found  and  a 
furnace  was  started,  but  is  not  now  in  operation.  Near  the  famous  lead- 
mining  town  of  Linares,  in  the  province  of  Jaen,  cinnabar  occurs  along 
the  partings  between  strata. 

Cinnabar  occurs  at  La  Creu,  in  the  province  of  Valencia.  I  have  had 
an  opportunity  of  examining  a  series  of  specimens  from  this  locality  in  the 
museum  of  the  Technical  High  School  of  Aachen.  The  country  rock  is 
sandstone.  The  gangue  minerals  are  quartz  and  carbonates,  with  which 
the  cinnabar  is  intimately  mingled.  Pyrite  is  also  abundant.  The  ores 
occur  in  veinlets  in  the  rock,  and  some  of  the  cavities  have  not  been  com- 
pletely filled.  The  absolute  impregnation  is  slight. 

Cinnabar  is  also  found,  according  to  Noggerath,  in  the  province  of 
Teruel,  in  a  cupriferous  quartz  vein,  and  the  same  sulphide  has  been  recog- 
nized in  the  provinces  of  Castellon  and  Alicante,  on  the  east  coast  of  Spain. 
Finally  it  occurs,  according  to  the  same  authority,  in  western  Spain,  in  the 
province  of  Badajos.  The  Almaden  district  is  close  to  the  boundary  of 
Ciudad  Real  and  Badajos,  and  a  small  part  of  it  lies  in  the  latter  province. 
Excepting  at  this  point  I  could  learn  of  no  occurrence  in  Badajos. 

France. — No  important  quicksilver  deposit  has  ever  been  opened  in 
France,  though  during  the  last  century  quicksilver  ores  were  mined  at 
Menildot,  in  the  department  of  Manche,  in  northeastern  France.  This 
mine  had  a  considerable  production  from  1730  to  1742.1  A  mine  is  said 
to  have  been  worked  recently  at  Prunieres,  in  the  department  of  Isere, 
somewhat  over  twenty  miles  from  Grenoble.  This  statement,  however,  is 
erroneous.  Mr.  II.  Kuss,  of  the  French  mining  service,  who  is  stationed 
at  Grenoble,  writes  me  that,  from  1850  to  1854,  explorations  were  made  at 
this  locality,  but  without  success.  The  principal  vein  carried  small  quan- 
tities of  blende,  calamine,  tetrahedrite,  and  galena,  and  the  vein  matter  was 

1  Burat :  G6o\.  appl.,  vol.  2,  p.  i:;i>. 


FEENCH  LOCALITIES.  33 

sometimes  stained  bright  red  with  finely-disseminated  cinnabar,  particularly 
in  the  neighborhood  of  calamine.  The  gangue  was  calcite  and  the  inclosing 
rock  was  dolomitic  limestone  of  the  Lias.  The  veins  were  very  irregular 
and  before  long  disappeared  altogether.  The  proportion  of  cinnabar  was 
always  very  small  and  no  metal  was  produced.  At  Chalanches,  in  the 
same  department,  it  is  found  with  sulphides  of  lead  and  zinc  in  veins,  in- 
closed by  crystalline  schists  which  contain  traces  of  platinum.  At  Alle- 
mond,  also  in  Isere,  cinnabar,  native  quicksilver,  and  silver  amalgam  occur 
in  a  vein.  In  central  France,  at  Peyrat,  in  the  department  of  Haute- 
Vienne,  native  quicksilver  is  found  in  a  decomposed  granite.  In  and  near 
the  Cevennes  Mountains,  also  in  southern  France,  native  quicksilver  occurs 
(e.  g.,  near  Montpellier)  in  Tertiary  or  Quarternary  beds.  This  locality 
was  discovered  in  1760. 

The  regions  in  which  quicksilver  has  been  found  in  France  also  con- 
tain other  metals,  as  is  not  unusual  in  other  countries.  In  Manche,  blende, 
calamine,  and  galena  are  found;  in  Haute-Vienne,  lead,  antimony,  and  tin; 
in  Isere,  lead,  silver,  and  gold;  in  Hdrault  and  Aveyron,  tetrahedrite  and 
galena.1 

On  the  island  of  Corsica  cinnabar  is  said  to  occur  in  a  state  of  great 
purity  in  the  Balagna,  in  the  territory  of  the  commune  Occhia  and  can- 
ton of  Belgodere.2  The  Balagna  is  a  district  lying  east  of  Calvi,  on  the 
north  coast  of  Corsica,  and  its  port  is  lie  Rousse.  Interesting  deposits  of 
cinnabar  are  found  on  Cape  Corso,  the  northern  promontory  of  the  island. 
It  is  found  with  stibnite  in  granite  (pegmatite),  serpentine,  euphotide,  schists, 
and  serpentiniferous  limestone.  With  stibnite  it  forms  crusts  of  a  few  cen- 
timeters in  thickness  occupying  fissures  in  the  rocks.  The  gangue,  when 
there  is  any,  is  quartzose.  Pyrite,  a  little  blende,  and  native  sulphur  are 
found  in  some  veins,  and  arsenic  lias  been  detected.  Mr.  Hollande  states 
that  the  fissures  have  been  filled  through  the  action  of  hot  springs.3 

itaiy. — Cinnabar  is  widely  distributed  in  Italy  and  Sicily,  though  most 
of  the  occurrences  are  of  very  small  importance.  The  northern  part  of 
the  Venetian  state  is  contiguous  to  Carniola,  in  which  lies  the  Idria  mine. 

1  Burat:  G6ol.  appl.,  vol.  2. 
2Noggerath,  loc.  cit. 

3D.  Hollamle:  Bull.  Soc  gdologique  France,  1675-1876,  vol.  4,  Paris,  1876,  p.  31. 
JION  XIII 3 


34  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Both  the  Austrian  and  Italian  portions  of  this  region  show  many  deposits 
of  cinnabar,  of  which  not  a  few  have  been  exploited  to  some  extent.  The 
most  famous  of  the  Italian  mines  in  this  region  is  the  Vallalta,  near 
Agordo.1  The  deposit  occurs  at  and  near  the  contact  between  a  mass 
of  quartz  porphyry  and  sedimentary  rocks  of  Triassic  age,  consisting  of 
sandstones,  shales,  graphitic  slate,  limestone,  and  a  certain  conglomerate. 
The  deposit  is  irregular  in  width,  but  follows  the  porphyry  and  ends  in 
strike  with  this  eruptive  rock.  The  cinnabar  is  found  as  impregnations  in 
the  porphyry  and  in  the  sandstone  and  as  stringers  in  the  shales,  but  the 
great  mass  of  it  is  in  the  conglomerate,  which  does  not  seero  to  be  found 
except  in  the  deposit  The  matrix  of  the  conglomerate  is  commonly  tal-_ 
cose,  and  embedded  in  it  are  rounded  pieces  of  gypsum,  calcite,  quartz, 
limestone,  and  porphyry.  Small  grains  and  stringers  of  cinnabar  are  scat- 
tered through  the  rock.  The  ordinary  material  of  the  deposit  contains 
only  two-tenths  to  1  per  cent,  of  quicksilver,  but  the  impregnation  of  cinna- 
bar increases  in  some  places  to  such  an  extent  that  the  greater  part  of  the 
ground-mass  is  ore,  inclosing  fragments  of  gypsum,  calcite,  and  quartz,  as 
well  as  foils  of  magnesian  mica.  Professor  vom  Rath  estimated  the  metal- 
lic contents  in  such  a  case,  from  the  specific  gravity  of  the  mass,  at  no  less 
than  24  per  cent.  The  deposit  is  intersected  by  numerous  veins  of  cinna- 
bar, accompanied  by  seams  of  gypsum.  The  only  sulphide  accompany- 
ing the  ore  is  pyrite,  crystals  of  which  are  often  embedded  in  the  cinnabar. 
At  the  contact  between  the  ore  body  and  the  graphitic  slate  metallic  quick- 
silver was  found.  Professor  vom  Rath  expresses  no  opinion  as  to  the  ori- 
gin of  this  deposit,  but  in  the  light  of  what  is  now  knoM  n  of  the  occur- 
rence of  quicksilver  I  should  suppose  that  the  ore  had  reached  its  position 
along  a  fissure  at  or  near  the  contact  between  the  porphyry  and  the  adja- 
cent rocks.  The  so-called  conglomerate  would  seem,  from  its  constituents, 
to  be  more  strictly  a  breccia  formed  by  movements  prior  to  the  deposition 
of  ore.  The  precipitation  of  gypsum  and  cinnabar  must  have  been  in  part 
simultaneous,  since  some  of  the  gypsum  is  reddened  by  admixture  of  ore. 
The  occurrence  of  native  quicksilver  in  contact  with  graphitic  rock  (and,  so 
far  as  reported,  there  only)  is  suggestive  of  reduction.  The  copper  depos- 

ilird  liy  (i.  VOID  Path:  Zeitsclir.  Driitscli.  gcol.  Gesell.,  vol.  Hi,  t«i4,  p.  121. 


ITALIAN  LOCALITIES.  35 

its  near  Agordo  are  in  the  same  series  of  rocks  and  at  no  great  distance. 
The  production  of  the  Venetian  mines  has  never  been  large  and  of  late 
years  has  become. insignificant.  Some  data  are  given  in  Chapter  I. 

Traces  of  cinnabar  are  found  in  Loinbardy  in  quartzite,  but  the  quantity 
is  nowhere  considerable.1 

In  Tuscany  numerous  deposits  of  quicksilver  occur  in  a  belt  about 
one  hundred  and  twenty-five  miles  in  length,  running  parallel  to  the  west 
coast  and  at  an  average  distance  of  about  twenty  miles  from  the  ocean. 
The  southern  end  of  this  series  of  deposits  is  at  Mt.  Amiata.  The  Levigli- 
ani  mine,  near  Serravezza,  at  the  northern  end  of  the  belt,  was  known  as 
early  as  1163.  The  cinnabar  is  accompanied  by  guadalcazarite,  siderite, 
and  pyrite  in  a  quartz  gangue  and  occurs  in  steatitic  schists  in  small  irregular 
veins.  The  chief  mines  of  this  belt  are  at  its  southern  extremity.  Amiata 
is. a  great  trachytic  mass  resting  upon  rocks  which  are  Post- Jurassic  and 
probably  Eocene.  They  are  for  the  most  part  calcareous.  All  around  the 
edge  of  the  lava  and  in  the  Eocene  rocks  occur  quicksilver  deposits,  many  of 
which  have  been  exploited.  Mr.  B.  Lotti  also  found  cinnabar  in  the  trachyte 
itself,  near  its  edge,  showing  that  the  deposits  are  later  than  the  eruption. 
The  principal  mine  is  the  Siele,  about  five  kilometers  from  Selvena.  This, 
as  described  by  d'Achiardi,  is  sunk  on  a  stratum  of  marl  many  meters  in 
thickness,  which  is  impregnated  with  cinnabar.  Stringers  of  calcite,  spotted 
with  cinnabar,  are  frequent  in  this  deposit.  The  same  author  gives  geolog- 
ical notes  on  several  Italian  mines  not  mentioned  here. 

Cinnabar  occurs  at  La  Tolfa,  not  far  from  Civita  Vecchia,  associated 
with  fluor-spar  and  blende. 

Xoggerath  writes  :  "At  Vesuvius  the  occurrence  of  quicksilver  is  very 
doubtful.  Fr.  Hoffmann,  in  his  history  of  geognosy,  speaking  of  the 
products  of  Vesuvius,  says  that  among  the  metallic  substances  Dolomieu 
mentions  also  quicksilver  and  stibnite,  but  they  have  never  since  been  found, 
as  Breislack  explicitly  states  ;  hence  an  error  seems  to  have  been  made  here." 
On  referring  to  Hoffmann's  history-  it  does  not  appear  to  me  that  he  intends 
to  ascribe  to  Dolomieu  the  assertion  that  at  Vesuvius  he  found  quicksilver. 

1  A.  d'Achiardi,  loc.  cit. 

^Geschichte  der  Gcognosie  imd  Schilderuug  der  vulkaniscLcn  ErscbeiuuDgen,  Berlin,  ls'38,  p.  477. 


36  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

I  think  Hoffmann  means  to  deny  the  opinion  held  by  Dolomieu  that  quick- 
silver and  stibnite  are  volcanic  emanations.  Dolomieu,  in  his  treatise  on 
volcanic  products,1  does  classify  these  minerals  as  products  of  sublimation, 
but  I  have  been  unable  to  find  any  passage  in  his  writings  in  which  he  men- 
tions having  observed  them  at  Vesuvius.  In  his  Voyage  aux  iles  de  Lipari 
I  find  no  allusion  to  the  subject.  It  may  be,  ho  wever,  that  in  some  of  his 
less  known  writings  he  gives  the  facts  upon  which  his  opinion  was  based. 

Noggerath,  writing  in  1862,  makes  the  comment  that  one  may  assent  to 
Hoffmann's  view  of  the  matter  the  more  readily  because,  thus  far,  quicksil- 
ver has  nowhere  been  found  in  volcanic  rocks,  but  since  1862  cinnabar  and 
quicksilver  have  been  often  found  in  volcanic  rocks,  and  cinnabar  and  stib- 
nite have  frequently  been  discovered  together.  Prof.  E.  de  Chancourtois, 
in  his  lectures  at  the-ficole  des  Mines,  has  been  in  the  habit  of  showing 
specimens  of  cinnabar  and  realgar  which  he  found  at  Pozzuoli,  near  Naples, 
at  the  opening  of  the  principal  fumarole,  and  which  had  been  deposited 
from  the  jet  of  aqueous  and  sulphurous  gases.2  Cinnabar  as  a  product  of 
volcanic  action  thus  exists  near  Mt.  Vesuvius,  if  not  upon  it. 

Noggerath  records  six  localities  in  Sicily  in  which  traces  of  cinnabar 
have  been  found,  but  without  any  details  as  to  occurrence  or  association. 
One  of  the  localities,  Paterno,  ten  miles  northwest  of  Catania,  is  at  the  base 
of  Mt.  JEtna.  It  would  be  very  interesting  to  know  what  relation  this  oc- 
currence bears  to  the  lavas  and  hot  springs  which  must  exist  not  far  from 
it.  I  have  been  unable  to  learn  anything  further  about  it. 

Germany. — The  quicksilver  deposits  of  Rhenish  Bavaria  have  lost  all 
the  commercial  importance  they  once  possessed,  but  not  their  geological 
interest.  They  have  been  very  fully  described  by  Prof.  H.  von  Dechen3 
and  a  digest  appears  in  von  Cotta's  Ore  Deposits.  It  is  therefore  un- 
necessary to  dwell  upon  them  here.  The  deposits  formed  veins  in  rocks 
of  Carboniferous  age,  and  to  some  extent  impregnations  in  sandstones. 
They  were  accompanied  by  a  melaphyre  (probably  diabase),  and  ore  was 
sometimes  found  in  spots  and  cracks  in  this  rock,  but  a  connection  between 

1  Journal  de  physique,  do  chiuiie,  d'histoire  uaturelle  et  des  arts,  Jean  Claude  LainetLerie,  vol.  1, 
1794,  p.  102. 

-Holland:  Bull.  Soc.  uiineralogique,  vol.  1, 1878,  p.  99. 
3  Archiv  fiir  Mineral.,  Karstcu,  vol.  22,  1848. 


PALATINATE  MINES.  37 

its  eruption  and  the  genesis  of  ore  was  not  established.  The  cinnabar  was 
accompanied  by  pyrite,  copper  ores,  and  lead  and  silver  minerals,  but  these 
were  for  the  most  part  rare.  The  gangue  was  composed  of  calcite,  quartz, 
chalcedony,  and  heavy  spar,  and  bituminous  matter  was  not  infrequent. 
They  were  richest  at  the  top  and  gave  out  in  depth.  It  is  an  interesting 
fact  that  cinnabar  occurred  in  these  mines  as  a  fossilizing  mineral,  having 
replaced  organic  remains,  for  this  seems  to  prove  that  organic  matter  may 
precipitate  cinnabar  from  solutions. 

Metacinnabarite  seems  to  have  occurred  in  these  mines,  for  von 
Dechen1  twice  mentions  among  the  ores  Quecksilber-Mohr,  though  without 
any  remark.  This  name  is  the  German  equivalent  of  2Elliiops  mineralis 
and  means  amorphous,  black,  mercuric  sulphide,  produced  by  grinding 
together  metallic  quicksilver  and  sulphur.  It  seems  impossible  that  this 
geologist  should  have  applied  this  designation  without  ascertaining  the 
chemical  character  of  the  compound  and  very  strange  that  he  should 
have  made  no  comment  on  the  novelty  of  the  mineral.  Analyses  and 
descriptions  of  this  mineral,  as  it  occurred  at  the  Redington  mine,  were 
first  published  by  Dr.  G.  E.  Moore  in  1870.  It  is  curious  that  the  Neues 
Jahrbuch,  in  reporting  von  Dechen's  monograph,  quoted  his  conclusions 
almost  word  for  word,  but  omitted  Quecksilber-Mohr  from  the  list  of  ores. 

No  other  quicksilver  mines,  so  far  as  I  am  aware,  have  been  worked 
in  Germany,  though  cinnabar  and  quicksilver  have  been  detected  at  nu- 
merous points  and  a  little  of  the  metal  has  been  secured  in  the  course  of 
the  treatment  of  ores  of  other  metals.  The  occurrences  have  so  often  been 
described  that  no  detailed  notice  is  necessary,  but  a  few  instances  may  be 
cited.  In  Bavaria,  near  Neustadt,  cinnabar  was  found  in  masses  of  quartz 
inclosed  in  granite.  In  Saxony,  near  Lossnitz,  it  has  been  recognized  in 
quartz  inclosed  in  crystalline  schists.  In  the  Harz  Mountains  cinnabar 
occurs  at  numerous  points.  The  Rammelsberg  mine  (iron  and  copper 
pyrites  and  galena)  contains  a  small  quantity  of  mercury.  At  Tilkerode 
and  Clausthal  tiemanite  and  mercurial  clausthalite  (lead  selenide)  are  found. 
Cinnabar  has  been  found  in  veins  crossing  early  Paleozoic  rocks,  with 
heavy  spar  and  siderite,  in  the  Hiilfe  Gottes  mine.  At  Kreuznach  and 


1  Archiv  fur  Mineral.,  Karstcn,  pp.  430 


OT 

UNIVERSITY 


38  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPK. 

other  points  in  Prussia  cinnabar  occurs  in  veins  traversing  eruptive  and 
.sedimentary  rocks.  These  cases  would  lead  one  to  suppose  that  cinnabar 
occurs  in  much  the  same  manner  as  other  metallic  sulphides. 

Austria. — TJic  deposits  of  Idria  were  discovered  during  the  closing 
.years  of  the  fifteenth  century.  After  a  number  of  vicissitudes  they  passed 
into  the  hands  of  the  state  and  have  been  worked  by  the  government  for 
public  account  ever  since  the  year  1580. 

The  geology  of  these  mines  is  of  great  interest,  for  not  only  has  it  been 
studied  with  the  closest  attention  by  highly  competent  geologists  daily  for 
many  years,  but  the  occurrences  are  such  as  to  throw  much  light  upon  the 
nature  of  the  deposit  and  the  method  of  genesis.  Mr.  M.  V.  Lipold,  as  a 
member  of  the  Austrian  Geological  Surve}",  examined  and  mapped  the 
country  surrounding  the  mines  in  1856.  In  1SH7  he  took  charge  of  the 
mines,  and  in  1874  published  a  memoir  on  the  geology  of  the  deposits  and 
of  the  surrounding  region.1  In  1880  he  wrote  another  paper  upon  the  ore 
deposits.2  From  these  memoirs  the  information  given  below  is  chiefly  de- 
rived. In  1878  Mr.  Lipold  was  good  enough  to  accompany  me  through  the 
mines  under  his  charge.  My  stay  was  far  too  short  to  enable  me  to  add 
any  original  observations  to  those  which  the  director  -had  made ;  but,  since 
his  conclusions  appear  from  the  literature  not  even  yet  to  find  entire  accept- 
ance, I  may  state  that,  to  me,  the  presence  of  a  fissure  system  such  as  Mr. 
Lipold  described,  and  the  direct  dependence  of  the  distribution  of  ore  upon 
this  fissure  system,  seemed  proved  beyond  question. 

The  region  surrounding  Idria  is  composed  of  Carboniferous,  Triassic, 
and  later  rocks,  which  have  been  subjected  to  great  disturbances.  Of  these 
the  chief  is  a  compressive  strain,  the  axis  of  which  has  a  northwest  and 
southeast  direction.  This  strain  is  manifested  in  part  as  a  fold  and  partly 
also  by  a  dislocation.  The  faulting  has  taken  place  chiefly  upon  a  single 
northwest  and  southeast  fissure,  which,  however,  as  is  so  usual,  is  accom- 
panied by  other  fractures  parallel  to  it.  In  the  course  of  the  faulting  move- 
ment a  portion  of  the  Carboniferous  beds  have  been  driven  over  the  Triassic 
strata,  thus  inverting  the  natural  order.  This  fact  formerly  caused  the  age 

1  Jahrbuch  k.  k.  geol.  Reichsaustalt,  Wien,  vol.  24,  1874,  p.  425. 
.    "Das  k.  k.  Quecksillierwerk  zn  Idria,  1881. 


IDRIA.  39 

of  the  strata  in  which  the  ores  are  found  to  be  greatly  exaggerated,  but  sub- 
sequently inversion  of  the  strata  was  proved  both  by  structural  evidence 
and  by  the  discovery  of  satisfactory  fossils. 

The  principal  fissure  on  which  dislocation  took  place  can  be  traced  on 
the  surface.  It  is  also  exposed  in  the  mines,  where  the  crushing  and  crum- 
pling of  the  Triassic  beds  which  it  traverses  are  plainly  visible.  The  attend- 
ant parallel  fissures  are  likewise  exposed  by  the  workings.  The  Triassic 
strata  belong  to  various  subdivisions  of  the  Alpine  Trias  (Werfen,  Gutten- 
. stein,  Wengen,  and  Ikonca  groups).  Lithologically  they  consist  of  schists, 
sandstones,  and  more  or  less  dolomitic  limestones;  in  short,  of  all  the  chief 
varieties  of  sedimentary  rocks.  All  of  these  stratigraphical  divisions  and 
all  of  the  lithological  varieties  of  rock  carry  more  or  less  ore  in  the  neigh- 
borhood of  the  fissures,  while  none  of  the  rocks  carry  ore  outside  of  the 
region  of  disturbance.  Furthermore,  the  deposits  lie  along  the  fissures,  hav- 
ing the  same  strike  and  dip  as  these.  There  is  thus  abundant  evidence  that 
the  ore  deposition  and  the  fissure  system  are  directly  related. 

The  form  of  the  deposits  differs  greatly  in  various  parts  of  the  ore-bear- 
ing region:  To  the  southeast  the  fissures  cut  across  the  beds  and  the  ore 
forms  true  and  unmistakable  veins  filled  with  wall-rock,  cinnabar,  and  gangue 
minerals.  In  the  northern  part  of  the  mine  the  fissure  for  some  distance 
follows  the  planes  of  bedding  of  the  Triassic  rocks  and  the  ore  is  inter- 
posed between  the  beds  somewhat  as  if  it  were  a  stratum.  The  cinnabar  is 
found,  however,  not  only  between  strata  and  impregnating  strata,  but  in  the 
cracks  penetrating  the  sedimentary  beds,  showing  that  the  deposition  fol- 
lowed the  disturbance  and  that  the  coincidence  of  the  fissure  and  the  planes 
of  bedding  was  due  only  to  the  fact  that  these,  when  nearly  vertical,  were 
surfaces  of  least  resistance.  In  short,  this  is  a  bed  vein,  that  is,  a  vein  which 
happens  to  coincide  in  direction  with  the  stratification.  In  the  same  part 
of  the  mine  a  portion  of  the  lower  Triassic  limestones  and  dolomites  have 
been  crushed,  and  the  deposit  assumes  the  form  of  an  irregular  reticulated 
deposit  or  stockwork.  Where  the  rock  is  sandy  or  porous,  impregnations  are 
found. 

The  mineralogical  character  of  the  ore  is  extremely  simple.  Cinnabar 
is  the  prevailing  mineral,  of  course.  Native  quicksilver  is  found  in  small 


40  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

quantities,  especially  at  contacts  with  the  Carboniferous  beds.  Pyrite  is 
tolerably  abundant,  sometimes  associated  with  metallic  mercury.  No  other 
metalliferous  mineral  occurs.  The  usual  gangue  minerals  are  quartz,  cal- 
cite,  and  dolomite,  and  they  have  been  deposited  simultaneously  with  the 
cinnabar.  Idrialite  occurs  in  shapeless  masses  and  is  especially  associated 
with  hepatic  cinnabar.  In  one  region  a  small  quantity  of  fluor-spar  has 
been  detected  with  cinnabar  and  dolomite.  Mr.  Lipold  regarded  the  asso-' 
elation  of  minerals  and  the  manner  of  their  occurrence  as  conclusively 
proving  that  the  ore  had  been  deposited  from  fluid  solutions,  a  conclusion 
which  appears  to  me  entirely  justifiable. 

This  mine,  unlike  others  in  southern  Austria  and  northern  Italy,  grows 
richer  as  its  depth  increases,  and  the  known  reserves  in  1880  were  sufficient 
to  maintain  the  production  at  the  current  rate  for  over  seventy  years. 

There  are  noteworthy  analogies  between  this  mine  and  that  of 
Almaden.  In  the  latter  the  ore  occasionally  crosses  strata,  though  usually 
following  the  stratification.  In  both,  reticulated  deposits  are  found,  though 
at  Idria  the  reticulated  mass  is  irregular  in  outline,  while  at  Almaden  it  is 
tabular.  Pyrite  is  the  only  foreign  metallic  mineral  abundant  in  either 
deposit.  In  both  a  part  of  the  deposits  follow  the  stratification  and  in 
both  there  is  evidence  of  disturbance  preceding  ore  deposition.  Impreg- 
nations occur  in  sandstone  in  each  mine.  Both  deposits  grow  stronger  as 
the  depth  increases.  Thus,  while  the  general  impression  produced  by  the 
two  chief  mines  of  cinnabar  is  different,  the  difference  is  one  rather  of  de- 
gree in  the  development  of  particular  features  than  of  fundamental  char- 
acter. Cinnabar  is  also  found  at  many  points  in  Carniola,  Styria,  Carin- 
tliia,  Salzburg,  and  the  Tyrol.  At  a  number  of  these  localities  small  quan- 
tities of  quicksilver  have  been  produced,  but  none  is  commercially  im- 
portant. The  mode  of  occurrence,  so  far  as  known  to  me,  is  in  each  case 
similar  to  that  of  other  deposits  more  or  less  fully  described  in  this  review. 

In  Bohemia  cinnabar,  quicksilver,  and  calomel  are  found  with  iron 
deposits.  At  Horowitz  the  quantities  obtained  were  so  considerable  that 
from  time  to  time  a  few  hundred-weight  of  quicksilver  were  produced  as  an 
incident  to  the  production  of  hematite.  The  latter  forms  a  bed  in  Silurian 
schists,  while  the  cinnabar,  accompanied  by  heavy  spar  and  pyrite,  is  found 


LOCALITIES  IN  EASTERN  EUROPE.  41 

in  cracks  in  the  schists  at  right  angles  to  the  bedding.1  In  specimens  which 
I  have  examined  calc-spar  also  is  present  The  reader  may  be  reminded 
that  at  Mieres,  also,  bodies  of  iron  ore  are  found  with  cinnabar. 

Hi-ngary. —  Though  mercurial  tetralred-rite  is  not  unknown  elsewhere, 
it  seems  particularly  characteristic  of  Hungary,  and  it  is  well  known  to 
metallurgists  that  small  quantities  of  quicksilver  have  been  obtained  for  a 
very  long  time  as  an  incident  to  the  roasting  of  copper  ores  in  the  Hun- 
garian Erzgebirge.  In  this  region  mercurial  gray  copper  ore,  pyrite,  cin- 
nabar, and  amalgam  occur  in  veins  inclosed  by  crystalline  schists  and 
gabbro,  usually  with  quartz  and  heavy  spar  as  gangue  minerals.  Ores  of 
antimony,  lead,  and  iron  are  also  found  with  those  of  quicksilver.  One 
variety  of  the  mercurial  tetrahedrite  contains  no  less  than  16.7  per  cent,  of 
quicksilver. 

Cinnabar  and  quicksilver  also  exist  at  many  points  in  Transylvania, 
though  not  in  deposits  of  much  commercial  value.  Very  interesting  is  a 
vein  in  the  Carpathians,  between  Transylvania  and  Bakowina,  at  Thihuthal, 
which  occurs  at  the  contact  between  a  dike  of  lava  and  much-altered  argil- 
laceous schist.  The  vein  is  sixteen  inches  thick  and  is  filled  with  calcite, 
dolomite,  and  country  rock.  This  vein  matter  contains  streaks  and  bunches 
of  cinnabar.  Small  quantities  of  galena  and  zincblende  are  also  found  in  it.2 

servia. — An  important  deposit  of  cinnabar  was  discovered  in  Mt.  Avala, 
near  Belgrade,  in  1883,  or,  more  properly  speaking,  rediscovered,  since  the 
Romans  seem  to  have  opened  a  mine  upon  it.  This  deposit  has  formed 
the  subject  of  an  important  study  by  Prof.  A.  von  Groddeck.3  Ore  has 
been  found  at  six  points  near  Mt.  Avala.  These  localities  do  not  form 
a  straight  line,  but  are  distributed  over  a  triangular  space.  The  country 
rock  is  serpentine,  believed  to  be  an  alteration  product  of  an  enstatite- 
olivine  rock.  The  ore  is  mainly  cinnabar,  but  native  quicksilver  and  a  little 
calomel  are  found.  Pyrite  and  rnillerite,  finely  disseminated,  accompany 
the  cinnabar,  and  in  a  single  locality  galena  also  occurs.  The  gangue 

1  Von  Gotta :  Erzlagerstatteu,  part  2,  p.  204. 

"Ibid.,  part  2,  p. 269.  The  average  annual  product  of  quicksilver  in  Hungary  from  1864  to  1883, 
twenty  years,  is  said  to  have  been  26.C5  metric  tons,  or  772  flasks,  Spanish  standard  (Mineral  Resources 
U.  S.  1885,  p.  293). 

"Zeitschr.  filr  Berg-,  Hiltten-  und  Salinen  \vesen  im  preuss.  Staato,  vol.  33. 


42  QUICKSILVER  DEPOSITS  OF  TJTE  PACIFIC  SLOPE. 

minerals  are  chalcedony,  quartz,  calcite,  dolomite,  barite,  and  iron  oxides. 
Chrome  iron  is  disseminated  in  the  serpentine  and  the  gangue.  The  ore 
is  found  in  seams  and  stringers  of  quartz  and  heavy  spar,  which  intersect 
the  vein  matter  in  all  directions,  and  also  in  impregnations.  Prof,  von 
Groddeck  regards  the  deposits  as  intimately  related  to  a  fissure  system 
and  of  a  vein-like  character,  but  infers  from  the  micro-structure  of  the  ore 
that  it  has  in  part  replaced  serpentine.  In  a  series  of  specimens  from  Avala, 
shown  to  me  by  Professor  Arzruni  in  Aachen,  this  replacement  is  not  ap- 
parent. Messrs,  de  Prado,  Monasterio,  Kuss,  and  others  consider  a  portion 
of  the  ore  of  Almaden  to  have  been  substituted  for  sandstone  or  quartzite, 
and  Mr.  Lipold  believed  that  ore  had  replaced  a  part  of  the  Idrian  schist 
(Lagerschiefer).  One  would  expect,  in  all  these  cases,  to  find  descriptions 
of  rounded  kernels  of  rock  inclosed  by  more  and  more  angular  envelopes 
of  ore,  the  outermost  bounded  by  irregular  fissure  surfaces,  for  this  struct- 
ure is  usually  associated  with  pseudomorphism.  I  do  not  find  such  de- 
scriptions nor  have  I  seen  any  _such  occurrences  in  California,  where  cinnabar 
is  often  met  with  in  contact  with  serpentine,  sandstone,  and  schist.  Neither 
have  I  seen  anything  of  the  kind  at  Almaden,  at  Idria,  or  at  the  Tuscan 
mines. 

Turkey  in  Europe — Mr.  W.  Fischbach l  examined  workable  deposits  of  cin- 
nabar and  native  quicksilver  in  the  neighborhood  of  Prisren,  in  Albania. 
This  place  I  take  to  be  identical  with  Prisrend  or  Perserin,  eighty  miles 
east-northeast  of  Scutari  and  about  four  miles  from  the  river  Driu.  He 
also  reports  occurrences  at  Crescevo,  in  Bosnia.  There  is  a  town  Kreshevo, 
perhaps  equivalent  to  Crescevo,  near  Serajevo,  in  Bosnia.  Mr.  A.  Conrad2 
examined  deposits  in  the  Inatch  Mountains,  near  Serajevo.  They  are  in- 
closed in  schists  and  limestones  and  are  nearly  vertical,  sometimes  forming 
veins  and  sometimes  beds.  The  vein  matter  consists  of  country  rock,  cal- 
cite, and  dolomite.  The  cinnabar  inclosed  in  the  vein  matter  is  accompa- 
nied by  pyrite,  blende,  and,  it  would  appear,  by  traces  of  gold.  Some  of 
the  deposits  are  several  meters  in  thickness  and,  Mr.  Conrad  believes,  could 
be  exploited  with  profit  if  operations  should  be  intelligently  conducted. 

'Berg-  uml  hiittenm.  Zeitung,  vol.  32,  1873,  p.  109. 
"Revue  de  gfiol.,  vol.  5,  186.r>-'6C>,  p.  115. 


LOCALITIES  IN  EUROPE  AND  AFRICA.  43 

Mr.  Fisclibach  also  mentions  that  a  concession  has  been  granted  for  mining 
native  quicksilver  at  the  Dardanelles. 

Russia. —  Besides  some  points  in  the  Ural  Mountains,  which  will  be 
mentioned  under  the  head  of  Siberia,  a  discovery  of  cinnabar  was  made  by 
Mr.  Minenkoff  in  southern  European  Russia  in  1879.  The  locality  is  west 
of  the  Azof  railway,  between  the  stations  Nikitoffka  and  Gavriloffka,  and 
seems  to  be  about  eighteen  miles  southwesterly  from  the  town  of  Bachmut. 
The  deposits  consist  of  a  stratum  of  sandstone  overlain  by  clay  slate.  The 
ore-bearing  stratum  is  in  part  impregnated  with  cinnabar.  It  is  also  trav- 
ersed by  many  cracks,  in  which  well-developed  crystals  of  cinnabar  are 
found.  The  rocks  underlying  the  principal  stratum  are  likewise  fissured, 
and  the  cracks  in  it  also  are  sometimes  filled  with  cinnabar.  According  to 
Professor  Tschermak  galena  is  intimately  mingled  with  the  cinnabar.1  All 
the  rocks  belong  to  the  Carboniferous.  The  deposit  is  said  to  be  rich,  and 
exploitation  on  a  commercial  scale  was  commenced  in  1886,  as  Professor 
Arzruni  informs  me.  There  are  ancient  superficial  mine  workings  on  the 
metalliferous  beds.2 

AFEICA. 

Algeria. — Within  a  few  years  there  was  a  mine  called  the  Ras-el-Ma 
worked  fifteen  miles  southeast  of  Philippeville,  province  of  Constantine. 
Mr.  Tissot  states  that  this  deposit  occurred  in  the  nummulitic  limestone 
(Eocene)  immediately  at  the  contact  with  argillo-talcose  schists.  In  his 
opinion  the  metalliferous  emanations  were  derived  from  the  latter  rock. 
This  mine  was  patented  in  1861  and  abandoned  in  187C.  He  also  mentions 
a  very  regular  mercuriferous  vein  at  Taghit,  in  the  valley  of  the  Oued-Abdi. 
It  occurs  in  the  lower  Cretaceous.3  Mr.  A.  Heckmanns  informs  me  that  in 
the  province  of  Algiers,  near  Palestro,  at  a  locality  called  Douar  Guer- 
rouma,  there  are  typical  veins  in  upper  Cretaceous  limestone  which  carry 
decomposed  blende  and  lead  ores.  These  ores  contain  silver  and  quick- 
silver, the  latter  sometimes  to  the  extent  of  3i  per  cent.  The  quicksilver 
is  not  recovered  at  present. 

1  Tschermaks  mineral.  Mittheil.,  vol.  7,  1685,  p.  93. 

-  M.  Iliriakoff:  Geol.  Fiireuingens  Stockholm  Forhamll.,  vol.  8,  No.  6,  1836. 

"Texte  explicatif  de  la  carte  gdologique  de  Constantine,  pp.  59  and  05.     Also,  Notice  g6ol.  et  min., 
D<5p.  de  Constantine,  Exp.  univ.  de  Paris,  1878,  pp.  22  and  23. 


44  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

In  1876  the  Bey  of  Tunis  exhibited  a  collection  of  ores  illustrative  of 
the  resources  of  his  dominions.  The  chief  mineral  products  of  Tunis  in- 
clude lead  and  mercury.1 

ASIA. 

southwestern  Asia. — Near  Smyrna  Mr.  Fischbach  (loc.  cit.)  found  a  rich 
vein  of  cinnabar  accompanied  by  antimony  ore.  This  is  the  only  record  of 
quicksilver  in  Asia  Minor  in  my  possession.  Ibn  Mohelhel,  an  Arabian 
author  of  the  ninth  century,  reported  quicksilver  as  occurring  in  the  western 
portion  of  Zendjan,  in  Persia,  General  A.  Houtum  Schindler,  of  the  Persian 
army,  found  cinnabar  and  native  quicksilver  in  the  district  indicated  by 
Mohelhel.2  Cinnabar  occurs  with  gold  in  alluvial  washings.  Furthermore, 
cinnabar  and  native  quicksilver  are  found  inconsiderable  abundance  in  the 
basalt  of  the  district,  which  also  carries  realgar.  Sulphur,  too,  is  plentiful 
and  lead  and  silver  are  mined  near  by.  This  locality  would  appear  to  be  a 
solfataric  one,  not  dissimilar  to  those  of  California. 

In  Afghanistan  Captain  Hutton3  reports  that  quicksilver  is  mined  at 
latitude  31°  18',  longitude  62°  18'  30". 

Globules  of  the  metal  are  also  said  to  occur  in  a  cellular  lava  at  Aden.3 

Siberia. — Cinnabar  is  found  in  various  secondary  deposits  in  the  gold- 
mining  districts  of  the  Ural  Mountains;  for  example,  near  the  Beresowsk 
smelting  works,  near  Miask,  and  near  Bogoslowsk.  At  the  last  locality  pieces 
of  cinnabar  weighing  a  pound  and  a  half  have  been  found,  but  the  original 
deposits  of  ore  have  never  been  detected  in  this  region.4  In  the  auriferous 
sands  of  Olem-Trawiansk  cinnabar  occurs  in  large  pieces,  an  examination 
of  which  is  said  to  justify  the  conclusion  that  the  original  deposits  were 
quartz  veins.5  It  is  hard  to  see  how  such  fragments  can  justify  any  positive 
conclusion  as  to  the  form  of  the  deposits,  but  it  is  something  to  know  the 
nature  of  the  gangue.  Professor  Arzruni  informs  me  that  to  the  south  of 
the  district  in  which  Miask  is  situated  no  cinnabar  has  been  found,  while  to 
the  north  it  occurs  in  rolled  fragments  in  most  of  the  gold  placers. 

Cinnabar  also  occurs  at  the  Ildekansk  quicksilver  mine,  in  the  district 

1 J.  M.  Safford:  R?pt  Phila.  Intermit.  Kxh.  1870  to  Parliament,  vol.  3,  London,  1878,  p.  481. 

2  Jahrbuch  k.  k.  geol.  Reichsaustalt,  Wicn,  vol.  31,  1881,  p.  183. 

3  V.  Ball:  Economic  Geology  of  India,  p.  170. 

••N.  von  Kokscharow:  Matcrialen  zur  Mineral.  Russlaiuls,  vol.  6,  1870,  p.  'jri!!. 
»C.  Zincken:  Jterg-  niul  Iiiitti-nm.  /citnng,  vol.  :«),  1880,  p.  :IGO. 


THE  SIBERIAN  MIXE.  45 

of  Nertschinsk,  in  eastern  Siberia,  near  the  borders  of  Manchuria.  The 
ore,  which  has  only  been  found  in  small  quantities,  forms  little  veins  and 
bunches  in  yellowish-gray  limestone,  the  gangue  being  calcite  and  quartz. 
It  is  said  that  this  deposit  was  discovered  as  far  back  as  1759,  but  was 
worked  only  to  a  depth  of  thirteen  meters.  In  1 797  the  mine  was  reopened 
and  eleven  pounds  of  quicksilver  were  obtained.  In  1834,  exploration  in 
the  neighborhood  disclosing  nothing  more,  it  was  decided  to  abandon  the 
mine.  In  1837  a  four-inch  vein  was  found  in  the  hanging,  but,  although 
it  was  decided  to  work  the  mine,  nothing  was  done.  In  1853  prospecting 
was  resumed,  but  only  traces  of  ore  were  found.  It  has  not  been  worked 
since.1  A  specimen  of  the  ore  from  this  mine  was  exhibited  in  Philadelphia 
by  the  School  of  Mines  of  St.  Petersburg. 

Some  travelers  in  later  years  have  regarded  the  existence  of  a  quick- 
silver mine  in  Nertschinsk  as  altogether  mythical.2  It  certainly  existed, 
but  the  above  data  show  how  small  an  affair  it  was.  No  other  mine  so 
insignificant  has  probably  ever  been  so  famous.  Endless  fables  have  been 
circulated  as  to  the  inhuman  confinement  of  prisoners  in  the  poisonous 
atmosphere  of  this  mine.  It  is  highly  improbable  that  more  than  half  a 
dozen  miners  were  ever  at  work  in  it  at  one  time,  while  mercurial  poison- 
ing in  quicksilver  mines  occurs  only  where  native  quicksilver  is  abundant, 
a  very  rare  case  excepting  at  Almaden.  They  are  ordinarily  as  healthful 
as  any  other  subterranean  excavations.  Native  quicksilver  is  not  mentioned 
as  having  been  observed  at  Ildekansk.  The  Nertschinsk  district  also  pro- 
duced gold,  tin,  silver,  and  lead.  The  country  seems  chiefly  composed  of 
granite  and  crystalline  schists. 

Cinnabar  has  also  been  said  to  occur  in  Kamtschatka.3  I  do  not  know 
the  exact  locality,  nor  have  I  been  able  to  discover  on  whose  authority  the 
statement  was  made.  Mr.  George  Kennan  informs  me  that  while  he  was 
at  Anadyrsk,  on  the  Anadyr  River,  in  1867,  the  natives  (Chukchis)  assured 
him  that  native  quicksilver  occurs  in  the  neighborhood.  As  a  proof  of 
their  statements  they  brought  him  something  like  100  grammes  of  the 

1  Von  Kokscharow  (loc  cit.)  and  A.  Oserskij  :  Abriss  der  Geologic,  dor  Mineralreichthiimcr  und  dcs 
Horgbaues  von  Transbaikalien,  St.  Petersburg,  1867. 

''  Dr.  Henry  Lansdell  (Through  Siberia,  18812)  could  learn  of  no  quicksilver  miuo  at  Nertschiusk 
and  cited  other  authorities  to  the  same  effect. 

3  Noggerath,  loc.  cit.  — 


46  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

metal  in  a  glove.  Mr.  Kennan  considers  it  almost  impossible  that  this 
quicksilver  can  have  been  obtained  by  the  natives  from  Europeans,  either 
by  design  or  by  accident,  arid  believes  that  it  represents  an  actual  occur- 
rence. He  was  not  shown  any  cinnabar. 

china. — Mr.  R.  Pumpelly  discovered  in  Chinese  literature  records  of 
the  occurrence  of  quicksilver  in  ten  of  the  eighteen  provinces.1  The  only 
province  certainly  known  to  contain  important  deposits  is  Kwei-Chau.  Of 
this  locality  Baron  F.  von  Richthofen  writes  as  follows:2 

Quicksilver  has  been  from  of  old  the  chief  commercial  product  of  Kwei-Chau.  At 
the  beginning  of  the  present  century  it  was  still  among  the  regular  articles  of  export 
from  Canton.  Then  it  failed  and  became  an  article  of  import,  rising  gradually  in 
quantity  until  it  reached  the  figure  of  over  10,000  piculs  [a  picul  being  133J  pounds] 
in  1831  and  1832.  Suddenly  the  Chinese  no  longer  required  the  foreign  quicksilver, 
and  from  1838  commenced  again  to.  export  it.  This  state  lasted  until  about  1849. 
Since  then  it  has  become  again  a  regular  article  of  import,  but  the  quantity  required 
is  much  less  than  in  former  years,  and  is  about  3,000  or  4,000  piculs  annually.  These 
alternate  flood  and  ebb  tides  were  probably  caused  by  the  periodical  disturbances  in 
Kwei-Chau.  When  the  last  one  commenced,  in  1848,  the  mines  were  abandoned,  and 
they  have  not  been  reopened  since.  [The  minister  of  the  Chinese  Empire  to  the 
United  States  informs  me  that  of  late  years  mining  has  been  resumed.] 

The  places  where  the  quicksilver  occurs  appear  to  be  limited  to  a  well-defined  belt 
which  extends  through  the  whole  province  from  southwest  to  northeast  [over  300 
miles].  One  of  the  principal  mining  districts,  and  the  only  one  in  regard  to  which  I 
was  able  to  get  some  information,  was  Kai-Chau  (in  Kwei-Yang-Fn).  The  mines  there 
were  scattered  over  an  area  of  10  li  diameter  [about  3£  miles]  *  *  *  I  was  una- 
ble to  get  a  clear  idea  regarding  the  mode  of  occurrence  of  the  ore,  but  it  is  said  to 
exist  in  considerable  quantity  and  to  have  been  difficult  to  mine  only  on  account  of 
the  presence  of  much  water.  *  *  *  The  mines  have  the  advantage  of  being  near 
Wang-Ping-Chau ;  the  metal  can  therefore  conveniently  and  cheaply  be  shipped  to 
Hang-Kow  [a  treaty  port].  *  *  *  The  number  of  places  at  which  quicksilver  is 
found  and  was  mined  is  so  great  as  to  make  it  not  improbable  that  in  respect  to  the 
quantity  of  this  metal  awaiting  extraction  Kwei-Chau  is  far  ahead  of  any  other  known 
quicksilver-producing  country  on  the  globe.  In  many  places  cinnabar  is  brought  to 
the  surface  in  plowing  the  fields. 

Since  Baron  von  Richthofen  is  a  mining  geologist  of  the  first  rank  and 
was  familiar  with  the  quicksilver  deposits  of  Austria  and  California,  his 
opinion  as  to  the  resources  of  China  is  entitled  to  great  weight,  Kwei-Chau, 

1  Geological  Researches  in  China  etc.  The  provinces  are  Shen-Si,  Kan-Sn,' Shan-Tung,  Ngan-IIwui, 
Sze-Chuen,  Hu-Nan,  Kwei-Chau,  Cheh-Kiang,  Kwang-Tiing,  Kwang-Si. 

•Letter  VII  to  the  Shanghai  Board  of  Trade,  187-2,  p.  81.  Prof.  J.  D.  Whitney  has  been  kind 
enough  to  furnish  mo  with  a  copy  of  that  portion  of  this  rare  publication  bearing  on  the  province  of 
Kwei-Chau. 


CHINA  AND  JAP 


at  the  time  of  his  visit,  had  been  in  a  state  of  chronic  disorder  since  1848 ; 
indeed,  the  number  of  unburied  corpses  made  the  country  extremely  un- 
healthful.  Realgar  and  orpiment  are  exported  from  Kwei-Chau,  and  many 
other  metallic  ores  are  said  to  exist  therer  The  neighboring-  province  of 
Yun-Nan  is  the  auriferous  district  of  China.  According  to  d'Achiardi,  fine 
natural  crystals  of  cinnabar  have  reached  Europe  from  Yun-Nan. 

Thibet. — Thibet  lies  close  to  Yun-Nan  and  is  often  mentioned  as  a  locality 
in  which  cinnabar  occurs.  I  have  not  met  with  a  citation  of  authority  for 
this  statement  and  do  not 'know  the  exact  locality. 

corea. — Mr.  Pumpclly  (loc.  cit.)  ascertained  from  Chinese  records  that 
Corea  contained  cinnabar  deposits.  Mr.  Ernest  Oppert1  states  that  the 
province  of  Hoang-Hai  contains  deposits  of  quicksilver,  tin,  and  lead.  The 
geology  of  Corea  has  very  recently  been  investigated  by  Dr.  C.  Gottsche.2 
He  found  the  province  of  Hwang- Haido  (equivalent  to  Hoang-Hai)  princi- 
pally occupied  by  crystalline  schists,  through  which  older  and  younger 
eruptive  rocks  have  burst.  He  notes  the  presence  of  hot  springs  in  this 
province.  Other  portions  of  Corea,  under  similar  geological  conditions,  are 
auriferous. 

japan. — At  Shizu,  in  the  neighborhood  of  Sendai,  province  of  Rikuzen, 
very  thin  veins  of  cinnabar  occur  in  a  whitish  volcanic  rock.3  It  would  be 
interesting  to  know  whether  this  is  a  rhyolite  or  a  solfatarically  decomposed 
eruptive  rock  of  a  more  basic  type.  A  quicksilver  mine  has  been  worked 
near  Ainoura,  on  the  peninsula  of  Hirado,  in  Matsiira  Kori  of  Nagasaki 
Ken.  The  former  superintendent,  Mr.  Gower,  reports  that  the  exploitation 
was  stopped  in  consequence  of  a  discouraging  accident  to  the  reducing 
plant.  The  ore  consists  in  part  of  impregnations  in  sandstone  and  in  part 
fills  small  fissures  and  seams.  The  country  rock  belongs  to  the  Coal 
Measures.4 

British  India. — It  is  said  that  quicksilver  mines  formerly  existed  in  Cey- 
lon, near  Colombo,  and  that  the"  Dutch  exported  quicksilver  from  them  to 
Europe.5  In  the  Andaman  Islands,  also,  it  is  said,  quicksilver  used  to 

'  Voyages  to  Corea,  1830,  p.  171. 

•  Sitzungsberichte  dcr  Berliuer  Akademie,  vol.  36,  1886. 

* J.  G.  H.  Godfrey:  Quart.  Jour.  Geol.  Soc.  London,  vol.  34,  1878,  p.  555. 

«H.  S.  Mnnroe:  Trans.  Am.  last.  Min.  Eng.,  vol.  5,  1876-'77,  p.  29'J. 

s  J.  F.  Dickson:  Encyc.  Tint.,  9th  edition,  article  Ceylon. 


48  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

be  obtained.  The  rocks  here  are  similar  to  those  of  California  near  San 
Francisco.  Traces  of  native  mercury  are  reported  from  Madras. 

Dutch  India. — In  Borneo  cinnabar  has  long  been  known  to  exist.  At  the 
gold  diggings  of  Sarawak  small  rolled  fragments  of  cinnabar  are  found, 
and  the  antimony  ores,  of  which  the  district  yields  large  quantities,  also 
contain  some  mercury.  By  systematic  prospecting,  original  deposits  of  cin- 
nabar were  found  about  1867.  The  chief  deposit  is  at  a  hill  known  as 
Tagora.  The  rock  consists  of  partially  metamorphosed,  interbedded  shales 
and  sandstones.  The  ore  is  found  in  the  slate  and  more  rarely  in  the  sand- 
stone. It  is  a  very  irregular  deposit,  but  includes  vein-like  developments. 
Calcite,  heavy  spar,  and  pyrite  accompany  the  ore.  At  Gading,  a  few  miles 
west  of  Tagora,  stibnite  and  cinnabar  occur  together.  Cinnabar  was  first 
mined  in  1868.  The  product  in  1872  was  1,733  flasks;  in  1873,  1,505  flasks.1 
In  1880  the  value  of  the  quicksilver  produced  in  Sarawak  was  #G6,300.2 
Mr.  S.  B.  J.  Skertchly,  formerly  or  the  Geological  Survey  of  Great  Britain, 
informs  me  that  he  has  examined  alluvial  deposits  from  the  interior  of  north 
Borneo  containing  gold  and  cinnabar.  On  the  island  of  Sumatra,  in  the 
southern  part  of  the  Pedang  highlands,  in  the  neighborhood  of  Sibelaboe, 
fine  particles  of  cinnabar  accompanied  by  magnetic  iron  occur  in  crystal- 
line schists,  but  not  in  quantities  sufficiently  large  to  warrant  mining  oper- 
ations.3 Quicksilver  is  also  reported  from  the  island  of  Java  at  Samarang.4 

Spanish  India — Unimportant  quantities  of  quicksilver  ores  are  reported  to 
occur  in  the  Philippine  Islands.5 

Australia — Rev.  W.  B.  Clarke,  who  has  so  greatly  contributed  to  the 
elucidation  of  the  mining  geology  of  Australia,  wrote  as  follows  in  1875:" 

Some  years  since,  I  reported  on  the  occurrence  of  mercury  in  this  colony,  but  my 
expectation  of  the  discovery  of  a  lode  of  cinnabar  has  been  disappointed.    The  cin- 

'A.  H.  Everett:  Notes  on  the  Distribution  of  the  Useful  Minerals  in  Sarawak,  not  dated,  but 
seemingly  written  in  1874. 

*  Mining  Journal,  London,  1882,  p.  415.  This  value  corresponded,  at  the  London  prices  for  1880, 
to  about  2,000  flasks. 

a  R.  D.  M.  Verbeek :  Beschr.  Sumatra's  Westkust,  1883,  p.  5G2. 

4  D'Achiardi,  loc.  cit. 

6  This  note  is  derived  at  second  hand  from  J.  Roth  :  Geologische  Beschafl'enLcit  der  Philippinen. 

'Mines  and  Mineral  Statistics  of  New  South  Wales, etc.,  Sydney,  1875,  p, 201. 


AUSTRALASIAN  LOCALITIES.  49 

nabar  occurs  011  the  Cudgegoug  in  drift  lumps  and  pebbles,  and  is  pr.obably  the  result 
of  springs,  as  in  California.  In  New  Zealand,  and  in  the  neighborhood  of  the  Clarke 
River,  north  Queensland,  the  same  ore  occurs  in  a  similar  way. 

About  this  date  work  was  in  progress  on  a  quicksilver  mine  on  the 
Cudgegong,1  but  in  1876  the  official  reports  pass  it  over  in  silence.  In 
1878  specimens  of  cinnabar  and  quicksilver  were  exhibited  in  Paris,2 
but  no  information  was  afforded  concerning  the  character  of  the  deposits. 
Cinnabar  has  been  mined  at  the  Wilkinson  mine  in  Kilkivan,  fifty  miles 
from  Maryborough,  Queensland.3  According  to  the  prospectus  of  a  mining 
company  a  few  tons  of  quicksilver  were  extracted  in  Kilkivan  in  1885. 
Cinnabar  is  said  to  exist  in  West  Australia  also.4 

Mr.  Noggerath  reports  small  quantities  of  crystalline  cinnabar  in  a 
gold  vein  in  Bendigo  County,  Victoria.  This  very  interesting  occurrence 
is  not  mentioned  by  Mr.  William  Nicholas  in  his  catalogue  of  localities  of 
minerals  which  occur  in  Victoria,5  nor  by  Mr.  R.  B.  Smyth  in  his  Mines  and 
Mineral  Statistics  of  Victoria.0  The  observation  has  probably  never  before 
been  published  in  English.  The  same  author  mentions  gold  amalgam  at 
German  Reef,  on  the  Tarrangower. 

New  Zealand. —  As  long  ago  as  18GG  it  was  known  that  quicksilver 
occurs  a  few  miles  southeast  of  Omapere  Lake,  near  the  Bay  of  Islands. 
In  1870  Mr.  F.  W.  Ilutton7  visited  the  locality,  where  there  are  numerous 
springs,  hot  and  cold.  He  found  two  warm  sulphur  springs  accompanied 
by  mercurial  deposits.  The  sandstone  was  impregnated  with  native  mer- 
cury and  cinnabar.  He  also  detected  an  open  vein  a  quarter  to  a  half 
inch  in  width  in  the  sandstone,  lined  with  a  black  ore  of  mercury,  accom- 
panied by  sulphur  and  globules  of  quicksilver.  He  ascertained  that  this 
black  ore  was  a  sulphide  containing  some  iron.  Mr.  Hutton  thus  nearly 
anticipated  Dr.  G.  E.  Moore's  discovery  of  metacinnabarite.  This  ore  is 
now  known  to  occur  at  several  mines  in  California,  at  Huitzuco  in  Mexico, 

1  Annual  Report  of  the  Department  of  Mines,  New  South  Wales,  1875,  Sydney,  187G,  p.  31. 

2  Repts.  of  the  U.  S.  Commissioners  Paris  Univ.  Exp.,  1&78,  vol.  4,  p.  246. 

3  D.  do  Corhtzar,  loc.  cit. 

*R.  Acton:  Eucyc.  Brit.,  !Hh  edition,  article  Australia 
sGeol.  Survey  Victoria,  Kept.  Prog.,  1876,  p.  280. 
"Prepared  for  the  Victorian  exhibition,  1872. 
'Trans.  New  Zeal.  Institute,  vol.  3,  1870,  p. 253. 

MON  XIII 4 


50  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

and  in  Rhenish  Bavaria,  as  well  as  in  New  Zealand.  A  greasy  hydrocar- 
bon accompanied  the  deposit  described  by  Mr.  Ilutton.  Dr.  J.  Hector1 
gives  an  interesting  account  of  an  occurrence  at  Ohaeawai,  on  the  south 
side  of  Omapere  Lake,  and  therefore  near  Mr.  Hutton's  locality.  Hot 
springs  and  steam  escape  from  the  terminal  end  of  a  scoriaceous  stream  of 
lava,  which  has  emanated  from  conical  hills  on  the  south  side  of  the  lake. 
These  springs  deposit  a  brown  "sandstone"  in  laminated  beds.  This  inco- 
herent, granular,  silici&us  sinter  includes  fragments- of  the  surrounding 
vegetation.  It  also  contains  thin  layers  of  cinnabar-sand  and  globules  of 
metallic  mercury.  No  great  amount  of  the  ore  exists  in  the  sinter,  how- 
ever, and  its  interest  is  purely  scientific.  Prof.  A.  Liversidge2  reports 
rolled  fragments  of  cinnabar  from  Waipori,  and  native  quicksilver,  with 
copper  and  sulphur,  from  Tokomairiro. 

CONCLUSIONS. 

Incomplete  as  are  most  of  the  foregoing  notes  on  deposits  of  quick- 
silver ores,  they  seem  to  point  to  some  conclusions  which  are  not  likely  to 
be  much  modified  by  more  detailed  descriptions. 

Age  of  the  inclosing  rocks. —  From  the  crystalline  schists,  presumably  of 
Archaean  age,  to  Quaternary  beds,  strata  of  all  the  larger  groups  of  geo- 
logical formations  are  known  to  carry  cinnabar.  The  mere  age  of  the  in- 
closing rocks  cannot,  therefore,  be  a  controlling  factor  in  the  distribution  of 
mercurial  ores.  More  deposits  are  found  in  Pre-Tertiary  rocks  than  in  those 
of  Tertiary  or  Post-Tertiary  age,  a  fact  susceptible  of  very  simple  explana- 
tion Cinnabar  deposits  are  also  found  in  granite  and  in  eruptive  rocks, 
including  Post-Tertiary  basalts. 

Lithoiogicai  character  of  inclosing  rocks. —  Cinnabar  occurs  in  conglomerates,  sand- 
stones, limestones,  and  shales,  or  in  all  the  great  lithological  subdivisions 
of  unaltered  strata.  It  occurs  also  in  quartzites,  slates,  serpentines,  and 
crystalline  schists,  as  well  as  in  basic  and  acidic  volcanic  rocks.  Thus 
the  lithological  character  of  the  inclosing  rock  does  not  determine  the 
deposition  of  the  ore.  If  there  is  any  rock  for  which  cinnabar  seems  to 

1  Eept.  Geol.  Explorations,  1874-1876,  p.  5. 

2 Trans.  New  Zeal.  Institute,  vol.  10,  1877,  p.  502. 


DISTRIBUTION  OF  CINNABAR.  51 

exhibit  a  partiality  it  is  sandstone,  but  rich  deposits  are  common  in  lime- 
stone, shale  or  slate,  and  serpentine,  and  are  not  unknown  in  other  rocks. 
No  definite  relation  between  the  lithological  character  of  the  inclosing 
rocks  and  the  richness  of  deposits  is  apparent  from  the  descriptions. 

Relations  to  lines  of  disturbance Comparison    of   tllC  sketcll-Diap     (PL    II)     with 

any  physical  chart  of  the  globe  shows  that  the  quicksilver  deposits  bear 
a  most  intimate  relation  to  lines  of  disturbance.  The  great  mountain 
chain  of  Eurasia  includes  the  Pyrenees,  the  Alps,  and  the  Himalayas. 
This,  which  might  conveniently  be  called  the  Alpimalayan  chain,  breaks  up 
into  divergent  ranges  at  each  end,  or  in  Spain  and  China.  The  larger  part 
of  the  known  occurrences  of  Eurasia  are  distributed  along  the  Alpima- 
layan chain,  and  their  frequency  is  very  nearly  proportionate  to  our  knowl- 
edge of  the  regions  in  which  they  occur.  There  is  little  reason  to  doubt 
that,  when  Kurdistan,  Afghanistan,  and  Thibet  are  better  known,  quicksil- 
Arer  localities  as  yet  undiscovered  will  be  found.  At  the  western  end  of  the 
chain  the  quicksilver  deposits,  like  the  ranges,  scatter.  This  appears  also 
to  be  the  case  in  China,  since,  according  to  Mr.  R.  Pumpelly,  cinnabar  oc- 
curs in  ten  out  of  the  eighteen  provinces  of  China;  but  I  have  not  thought 
the  information  sufficiently  definite  to  justify  me  in  entering  the  localities 
on  the  map.  The  chief  localities  not  immediately  in  the  Alpimalayan 
chain  are  those  on  the  western  coast  of  Italy.  These  deposits  form  a  line 
which  may  manifestly  be  regarded  as  a  mere  offshoot  from  the  great  belt  of 
disturbance.  The  outlying  range  of  the  Ural  Mountains  is  marked  by  a 
few  traces  of  cinnabar.  The  famous  deposit  of  eastern  Siberia  seems  quite 
isolated.  The  occurrences  of  Kanitschatka  and  Japan  lie  along  a  line  of 
disturbance  marked  by  a  series  of  active  and  extinct  volcanoes,  and  the 
deposits  of  the  East  Indian  islands  are  associated  with  similar  evidences  of 
dynamic  action. 

The  American  deposits  from  Alaska  to  Chili  lie  near  the  coast,  along 
the  western  ranges  of  the  Cordillera  system,  and  the  line  in  which  they  oc- 
cur is  marked  from  one  end  to  the  other  by  manifold  evidences  of  profound 
disturbance.  The  Brazilian  deposits,  like  that  of  Nertschinsk,  are  in  mount- 
ainous, metalliferous  regions,  but  seem  only  remotely  connected  with  the 


52  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

main  line  of  mountains;  and  a  similar  statement  is  true  of  the  traces  of  cin- 
nabar found  in  Santo  Domingo  and  in  Nova  Scotia. 

The  deposits  of  Australia,  such  as  they  are,  lie  along  the  principal 
mountain  range  of  that  continent,  and  those  of  New  Zealand,  like  those  of 
the  East  Indies,  are  accompanied  by  evidences  of  disturbance  marked  by 
volcanoes. 

Relations  to  volcanic  phenomena. — In  a  few  cases  tli 6  deposition  of  cinnabar 
has  been  observed  at  the  vents  of  volcanic  emanations,  viz,  at  Pozzuoli 
in  Italy,  near  Lake  Omapere  in  New  Zealand,  and  'at  localities  on  the 
Pacific  Slope.  There  are  other  cases  in  which  cinnabar  is  immediately 
associated  with  hot  springs  and  sulphur  deposits  in  such  a  way  as  to  sug- 
gest the  former  existence  of  hot  sulphur  springs  of  volcanic  origin.  Such 
are  the  deposits  of  Guadalcazar  in  Mexico,  the  Baths  of  Jesus  in  Peru,  and 
those  of  Persia.  Hot  springs  exist  close  to  the  great  deposit  of  Huancave- 
lica,  but  whether  they  contain  sulphur  I  do  not  know.  Cinnabar  and  na- 
tive quicksilver  are  found  in  eruptive  rocks  a  part  of  which  are  recent,  in 
melaphyre  in  Rhenish  Bavaria,  quartz  porphyry  at  Vallalta,  trachyte  at  Mt. 
Amiata,  trachyte  or  basalt  in  Transylvania,  basalt  in  Persia,  pitchstone  por- 
phyry in  Mexico,  trachyte  in  Peru,  and,  I  may  add,  in  andesite  and  basalt 
in  California.  •  As  has  already  been  pointed  out,  cinnabar  also  occurs  along 
belts  marked  by  the  presence  of  volcanoes,  active  or  extinct.  This  is  espe- 
cially notable  in  Italy,  in  western  Asia,  New  Zealand,  and  throughout  the 
entire  American  series  of  deposits  from  Alaska  to  Chili. 

Mineral  association. — The  most  common  metallic  mineral  associated  with  cin- 
nabar is  pyrite,  and  this  sulphide  is  perhaps  never  entirely  absent,  though  it 
is  not  mentioned  in  some  of  the  descriptions.  It  is  so  common,  however, 
that  were  it  absent  in  any  deposit  mention  would  probably  be  made  of  the 
fact.  Traces  of  copper  sulphides  perhaps  come  next  in  frequency,  but  ar- 
senical and  antimonial  compounds  are  found  abundantly  in  some  deposits. 
The  quantity  of  arsenic  at  Huancavelica  seriously  interfered  with  the  work- 
ing of  the  ore,  and  livingstonite  is  an  important  ore  in  Mexico.  The  ore  of 
Mieres  is  like  that  of  Huancavelica.  Mr.  de  Chancourtois  found  realgar  with 
quicksilver  at  Pozzuoli ;  Dolomieu  is  said  to  have  found  cinnabar  and  stibnite 
on  Mt.  Vesuvius,  but  there  is  some  doubt  whether  this  geologist  made  such 


ASSOCIATED  ROCKS  AND  ORES.  53 

a  statement.  Antimony  accompanies  cinnabar  in  Corsica  and  at  Smyrna; 
realgar  and  cinnabar  are  found  together  in  Persia.  Realgar  is  one  of  the 
exports  of  the  quicksilver  region  of  China.  Gold  is  intimately  associated 
with  quicksilver  and  cinnabar  at  a  great  number  of  points,  sometimes  in 
veins,  but  oftener  in  gravels.  There  is  no  deposit  of  great  importance, 
however,  from  which  both  metals  can  be  profitably  extracted.  Ores  of 
copper  and  zinc  are  not  seldom  found  with  cinnabar ;  lead  and  silver  ores 
are  more  rare;  but,  as  in  the  case  of  gold,  it  is  seldom  that  valuable  de- 
posits of  any  of  these  metals  carry  important  quantities  of  quicksilver  or 
that  valuable  deposits  of  cinnabar  contain  important  quantities  of  the  other 
metals.  It  is  nevertheless  interesting  to  observe  that,  with  the  exception  of 
tin,  all  the  chief  metallic  ores  are  sometimes  deposited  together  with  cinna- 
bar. The  gangue  minerals  accompanying  cinnabar  are  nearly  always  either 
silica,  often  in  part  of  hydrous  varieties,  or  carbonates  in  which  calcite  pre- 
dominates. As  Mr.  d'Achiardi  remarks,  the  character  of  the  gangue  seems 
largely  determined  by  the  nature  of  the  adjacent  rock.  Baryte  and  fluor- 
spar are  not  infrequent  and  bituminous  matter  is  found  in  a  very  large  pro- 
portion of  quicksilver  mines. 

Form  or  the  deposits. — Except  in  the  case  of  gravels,  I  know  of  no  case  in 
which  it  is  clear  that  cinnabar  has  been  deposited  simultaneously  with  the 
other  material  of  stratified  rocks.  It  is  true  that  observers  have  not  infre- 
quently asserted  of  cinnabar  deposits  that  they  were  coeval  with  the  inclos- 
ing rocks,  but  the  only  ground  for  this  opinion  which  I  have  seen  given  is 
conformability  between  deposits  of  ore  and  the  surrounding  strata.  This 
is  by  no  means  adequate  to  establish  the  point  in  question.  In  most  cases 
it  seems  certain  that  the  deposition  of  ore  was  subsequent  to  some  disturb- 
ance of  the  country  rock.  In  these  cases  the  ore  is  deposited  in  interstitial 
spaces,  and  possibly  also  to  some  extent  by  substitution  for  rocks  or  other 
minerals.  There  is  no  doubt  that  true  veins  of  cinnabar  occui',  sometimes 
cutting  sedimentary  rocks  and  sometimes  following  the  stratification.  Re- 
ticulated masses  and  impregnations  are  also  common.  It  is  often  supposed 
that  the  characteristic  forms  of  cinnabar  deposits  are  not  to  be  brought 
under  any  of  these  categories ;  but  I  cannot  see  sufficient  evidence  in  the 
literature  to  prove  this  supposition.  Selvages  and  comb  structure  are  often 


54  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

absent,  and  sometimes  the  walls  of  vein-like  deposits  are  not  well  defined. 
But  veins  of  ideal  structure,  such  as  those  vipon  which  the  diagrams  of  text- 
books are  founded,  are  not  common  in  all  regions,  even  in  gold,  silver,  or 
copper  deposits.  Small  veins  in  hard,  coherent  rock  often  assume  this  sim- 
ple form,  but  large  veins  in  volcanic  or  partially  metamorphosed  rocks  are 
often  indistinctly  bounded  and  are  very  complex  in  structure.  In  many 
parts  of  the  Comstock  lode,  for  example,  there  is  no  definite  hanging  wall, 
and  the  bonanzas  of  that  great  vein  are  masses  of  brecciated  rock  filled  in 
with  ore.  So,  too,  the  gold  veins  of  California  are  in  great  part  bed  veins, 
a  fact  due  to  the  nearly  vertical  position  of  the  strata  before  the  deposition 
of  ore,  and  they  are  often  somewhat  indistinctly  defined.  In  short,  the  char- 
acter of  the  fissure  which  a  vein  fills  must  depend  on  the  physical  properties 
of  the  rock,  and  clean-cut  open  fissures  can  be  formed  only  in  appropriate 
material.  In  many  cases  a  fracture  will  produce  a  belt  of  crushed  country 
rock,  instead  of  an  open  crack,  and  the  ore  deposited  in  the  interstitial  space 
will  depart  to  a  corresponding  degree  from  an  ideal  vein.  Where  the  strata 
of  a  region  have  a  nearly  vertical  position  prior  to  the  formation  of  veins, 
bed  veins  must  prevail.  When  ore  is  deposited  in  contact  with  porous  rocks, 
such  as  many  sandstones,  impregnation  must  take  place.  The  chief  differ- 
ence between  an  impregnation  in  sandstone  and  the  injection  of  a  breccia  is 
that  in  the  former  case  the  interstitial  space  is  due  to  the  original  structure 
of  the  rock,  instead  of  being  brought  about  by  dynamic  action  accompany- 
ing the  formation  of  the  main  fissure.  Impregnations  of  other  ores,  as  well 
as  those  of  mercury,  are  not  uncommon. 

Mr.  Lipold  showed  conclusively  that  the  deposit  of  Idria  consists  of 
simple  veins,  reticulated  masses,  and  impregnations.  Evidence  is  given 
above  which  tends  to  show  that  the  deposit  of  Almaden  is  similar,  except 
that  the  reticulated  masses  are  tabular  and  vein-like  and  that  bed  veins 
greatly  predominate  over  those  which  cut  the  beds.  Ilumboldt's  descrip 
tion  of  Huancavelica  shows  that  similar  conditions  there  prevail.  At  Yal- 
lalta,  also,  stringers  of  ore  pierce  the  shales,  the  porphyry  is  impregnated, 
and  the  main  mass  of  the  ore  seems  to  be  a  somewhat  tabular  or  vein-like 
stockwork.  In.  short,  all  the  better -known  deposits  are  referable  to  the 
three  forms  of  deposits  described  by  Mr.  Lipold,  and  I  know  of  no  sufficient 


SOURCE  OP  THE  ORE.  55 

evidence  to  justify  the  belief  that  cinnabar  occurs  on  a  large  scale  as 
deposits  coeval  with  the  inclosing-  rocks.  Cinnabar  is  not  known  to  exist 
as  cave-fillings.  Several  geologists  think  that  cinnabar  has  been  to  some 
extent  substituted  for  sandstone,  shale,  or  serpentine ;  but,  while  this  may 
be  true  to  some  extent,  this  process  does  not  seem  to  have  been  sufficiently 
rapid  to  impress  upon  the  deposits  the  peculiar  character  seen  in  some  lead 
mines.  The  hypothesis  of  the  substitution  of  cinnabar  appears  to  me  thus 
far  to  lack  sufficient  proof. 

Genesis  and  source  of  the  ore. — The  mineral  associations  in  which  cinnabar  is 
found  seem  to  show  conclusively  that  it  has  been  deposited  from  solutions. 
A  very  large  part  of  the  known  deposits  of  cinnabar  are  extremely  similar 
in  character,  a  fact  which  seems  indicative  of  a  similar  origin.  It  is  cer- 
tain that  some  of  the  deposits  are  due  to  precipitation  from  hot  volcanic 
springs  and  it  may  fairly  be  inferred  that  many  of  them  were  formed  in 
this  manner.  The  diversity  of  the  country  rocks  in  which  the  deposits 
occur  is  evidence  that  only  a  part  of  them  can  have  derived  their  metallic 
contents  from  their  own  wall  rocks;  the  remainder  must  owe  their  cinnabar 
to  some  source  between  the  point  at  which  the  waters  acquired  their  heat 
•and  the  surface.  Between  the  depth  at  which  volcanic  foci.  He  and  the 
surface  of  the  earth  there  must  be  substances  of  world-wide  distribution 
which  frequently  contain  mercury  in  some  form  as  an  original  ingredient. 
These  substances  are  probably  massive  rocks,  and  the  only  known  rock 
of  correspondingly  wide  distribution  is  granite. 

I  now  pass  to  the  geology  of  the  cinnabar  deposits  of  the  Pacific 
Slope.  After  describing  them  I  shall  return  to  the  subjects  mentioned  in 
these  conclusions. 


T7HI7ERSIT7 


CHAPTER  III. 

THE  SEDIMENTARY  ROOKS. 

General  character. — The  Coast  Ranges  of  California  present  a  truly  remarka- 
ble opportunity  for  the  investigation  of  some  of  the  most  important  phe- 
nomena embraced  under  the  general  term  of  metamorphism.  To  give  a  clear 
ideaof  the  unusual  advantages  afforded  by  this  area  it  is  necessary  to  anticipate 
s.ome  of  the  results  reached.  Field  examinations  were  made  for  this  memoir 
at  numerous  points  from  above  Clear  Lake  to  the  region  of  New  Idria,  thus 
partially  covering  a  belt  of  the  Coast  Ranges  about  230  miles  in  length. 
Throughout  this  whole  region  there  is  structural  and  lithologieal  evidence 
that  granite  of  very  uniform  character  underlies  the  entire  country.  Ex- 
cepting the  belt  of  schists  along  the  coast  from  Santa  Cruz  southward,  it 
is  estimated  that  90  per  cent,  of  all  the  rocks  of  this  region  are  sandstones, 
altered  or  unaltered.  These  sandstones  are  also  extremely  uniform  in  char- 
acter, and  wherever  they  are  inconsiderably  modified  the  slides  prepared 
from  them  show  that  they  are  directly  or  indirectly  derived  from  the  gran- 
ite, or,  in  other  words,  that  they  are  arcose.  Of  this  material  of  known 
origin  a  portion  has  been  highly  altered.  The  alteration  processes  to  which 
it  has  been  subjected  are  identical  from  one  end  of  the  region  to  the  other 
and  innumerable  transitions  are  presented.  It  is  difficult  to  estimate  the 
areas  occupied  by  the  metamorphic  rocks  of  the  Coast  Ranges,  because  the 
occurrences  are  extremely  irregular.  A  moderate  estimate  of  the  exposures 
between  Clear  Lake  and  New  Idria,  which  consist  of  holocrystalline  meta- 
morphic rocks,  sandstones  in  which  reerystallization  lias  made  considerable 
progress,  phthanites,  and  serpentine,  is  3,000  square  miles.  Large  areas, 
covered  by  late  Cretaceous  and  Tertiary  strata,  are  also  known  to  be  un- 
derlain by  metamorphics,  and  this  series  extends  far  to  the  north  and  to  the 


FACILITIES  FOR  STUDY  OF  METAMORPHISM.  57 

south  of  the  limits  indicated  without  substantial  change  in  character.  The 
study  is  thus  not  one  of  merely  local  recrystallization,  but  of  regional  meta- 
morphism,  which  is  not  of  uniform  intensity  and  is  therefore  the  better 
fitted  for  investigation. 

The  age  of  the  altered  beds  is  known,  from  direct  paleontological  evi- 
dence at  a  number  of  localities,  to  be  Neocomian,  and  there  is  no  evidence 
that  any  considerable  quantity  of  older  rocks  is  included  within  the  area. 
The  epoch  of  the  metamorphism  is  also  clearly  proved  to  be  in  the  earlier 
portion  of  the  Cretaceous  period,  and  probably  about  the  close  of  the  Neo- 
comian. 

The  most  interesting  alteration  processes  to  which  the  sandstones  have 
been  subjected  are  closely  similar  to  those  which  characterize  metamorphic 
areas  elsewhere,  consisting  chiefly  in  the  metasomatic1  recrystallization  of 
sediments  to  holocrystalline  feldspathic  rocks  carrying  ferromagnesian  sili- 
cates and  in  the  formation  of  vast  quantities  of  serpentine.  At  the  same 
time  these  rocks  present  peculiarities  distinguishing  them  from  many  highly 
altered  rocks  in  other  regions. 

The  metamorphism  accompanied  or  followed  an  upheaval  of  unusual 
violence.  In  tin's  uplift  the  granite  must  have  been  shattered  as  well  as  the 
overlying  strata.  The  metamorphism  was  chemically  of  such  a  character 
as  to  necessitate  the  supposition  that  solutions  rising  to  the  surface  from  the 
shattered  granite  beneath  co-operated  in  the  process. 

Thus  the  origin  of  the  sedimentary  rocks,  their  mineralogical  character 
in  an  unaltered  state,  their  age,  the  approximate  epoch  at  which  they  were 
metamorphosed,  and  the  general  character  of  the  conditions  of  metamor- 
phism are  all  known,  while  the  exposures  illustrating  the  comparatively 
few  more  important  problems  involved  are  numberless.  I  am  not  aware 
that  metamorphism  has  ever  been  studied  under  conditions  so  favorable  for 
elucidation.  It  is  unnecessary  to  say  that  the  material  is  far  from  ex- 
hausted by  a  single  investigation.  Much  remains  to  be  done,  especially 
from  a  chemical  point  of  view ;  indeed,  the  chemical  details  of  the  greater 
part  of  the  transformations  are  still  unknown. 

1  Jiy  metasomatism  I  uadi-i'stand  iiml  desire  to  express  a  change  <diV(;t<'d  by  the  action  of  mineral 
solutions  having  an  extraneous  origin,  but  not  necessarily  or  usually  involving  a  total  replacement  of 
the  material  acted  upon. 


58  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Hypotheses. —  Students  of  the  extremely  difficult  subject  of  metamorphism 
have,  no  doubt,  in  some  cases  been  tempted  to  put  forward  hypotheses,  to 
account  for  the  existence  of  crystalline  rocks,  which  were  warranted  neither 
by  detailed  observation  on  the  actual  series  of  changes  nor  by  any  known 
chemical  principles.  It  would  be  a  great  mistake  to  assume,  however,  ih.it 
careful  observations  on  actual  transformations  are  valueless  unless  they 
can  be  accounted  for  by  known  chemical  relations.  Even  the  structural 
formulas  of  many  most  important  minerals  are  still  in  doubt;  much  more  so 
is  the  complete  theory  of  their  formation;  while  recent  researches,  particu- 
larly those  of  Dr.  Wolcott  Gibb.s,  demonstrate  the  extreme  complexity  of 
many  inorganic  chemical  processes.  Though  there  can  thus  be  no  question 
as  to  the  existence  of  transformations  in  altering  rock  masses  for  which  no 
adequate  explanation  can  be  offered,  it  is  equally  true  that  observed  facts 
are  frequently  capable  of  two  or  more  explanations  and  that  the  relations 
of  mingled  products  are  often  susceptible  of  misinterpretation.  In  the 
present  investigation  great  care  has  been  taken  to  avoid  errors;  and  sev- 
eral hypotheses  as  to  relations,  in  support  of  which  considerable  evidence 
can  be  adduced,  have  not  been  admitted  on  the  ground  that  the  appear- 
ances might  after  all  be  deceptive.  It  is  believed  that  by  this  means  the 
errors  have  been  reduced  to  a  minimum  and  that  the  residual  observations 
and  inferences  recorded  in  'the  following  pages  afford  a  solid  foundation 
for  future  inquiry.  The  results  also  seem  sufficiently  definite  to  form  an 
important  aid  in  the  study  of  more  complex  metamorphic  areas  in  other 
parts  of  the  world.  That  the  conclusions  reached  are  applicable  to  other 
portions  of  California  is  almost  certain,  for  the  metamorphosed  rocks  of 
the  gold  belt  are  in  part  of  the  same  age  as  those  of  the  Coast  Ranges 
and  appear  to  be  strikingly  similar  in  lithological  character.  That  region 
is  .now  under  investigation  by  my  party,  and  it  is  believed  that  further 
interesting  results,  for  the  same  class  of  metamorphic  rocks  at  least,  will  be 
obtained  in  the  near  future.1 

1  It  is  probably  impossible  for  any  one  to  free  himself  from  the  influence  of  preconceptions.  It 
may  not  be  superfluous,  therefore,  to  state  that  in  beginning  the  investigation  of  the  quicksilver  belt  I 
entertained  no  opinions  on  the  character  of  the  crystalline  and  serpeutinoid  rocks.  1  was  quite  pre- 
pared to  find  the  former  either  eruptive  or  unaltered  crystalline  sediments  and  I  entertained  no  preju- 
dice against  regarding  serpentine  either  as  an  original  deposit  or  as  an  altered  olivine  rock.  I  still 
regard  it  as  not  improbable  that  crystalline  schists  and  serpentine  are  sometimes  original  precipitates 


FRAMING  OF  HYPOTHESES.  59 

It  is  well  known  that  eruptive  as  well  as  sedimentary  rocks  are  subject 
to  metamorphic  action,  and,  since  sedimentary  rocks  are  not  infrequently  of 
nearly  the  same  composition  as  eruptive  masses,  they  should  yield  analo- 
gous results  under  similar  circumstances!  The  study  of  metamorphics 
should  therefore  throw  light  on  the  transformations  of  eruptive  masses,  a 
study  most  intimately  connected  with  mining  geology.  It  will  appear  in 
the  sequel,  as  it  does  from  the  published  investigations  of  other  geologists, 
how  much  caution  should  be  exercised  in  deciding,  from  slides  of  altered 
eruptive  rocks,  what  mineral  constituents  are  secondary.  It  is  certain  that 
the  neglect  of  such  caution  has  more  than  once  led  lithologists  into  grave 
errors,  and  the  facility  with  which  it  appears  that  new  mineral  combina- 
tions take  place,  under  conditions  perhaps  not  greatly  different  from  those 
usually  prevailing,  strengthens  the  probability  that  deceptive  appearances 
are  even  more  common  than  has  hitherto  been  suspected. 

UNMETAMORPHOSED    SEDIMENTARY    ROCKS. 


Macroacopica!  character  of  the  rocks.  -  Excepting    the    light    d'Cam-Colored    Schists 

of  Miocene  age  which  occupy  a  narrow  strip  along  the  coast  of  California 
from  the  neighborhood  of  Santa  Cruz  southward,  the  rocks  of  the  quick- 
silver belt  where  unaltered  are  mainly  sandstones  of  Cretaceous  and  Ter- 
tiary age.  (See  Chapter  V.) 

The  sandstone  of  the  Coast  Ranges  often  occurs  in  practically  unin- 
terrupted series  of  beds  many  thousands  of  feet  in  thickness      Indeed,  the 

• 

observer  can  hardly  fail  to  wonder  under  what  mechanical  conditions  such 
vast  accumulations  of  sand  can  have  gathered.  This  problem,  presented  in 
many  regions,  though  perhaps  nowhere  else  on  so  large  a  scale,  has  never  I 
believe  received  a  satisfactory  solution.  From  the  Neocomian  to  the  Mio- 
cene the  predominant  rock  of  this  class  is  of  medium  grain  and  light  color, 
usually  yellowish  where  exposed,  bluish  at  some  depth  from  the  surface. 
The  Tejon  rock,  however,  is,  as  a  rule,  much  lighter  in  color  than  the  oth- 
ers, and  often  almost  white.  Induration  is  much  more  frequent  among  the 

and  do  not  doubt  that  highly  olivinitic  rocks  may  decompose  to  a  muss  substantially  composed  of 
serpentine.  For  the  Const  Ranges  of  California  and  in  part  for  the  gold  belt,  however,  careful  study 
has  led  me  to  very  different  conclusions;  but  I  do  not  hesitate  to  believe  that  every  mineral  has  been 
formed  somewhere  in  nature  by  every  possible  method  Real  peridotitic  serpentine  orrnrs  in  the  gold 
belt  and  has  be"n  carefully  compared  with  the  serpentine  of  t4ie  Coast  Ranges. 


60  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

*% 

older  sandstones,  but  is  not  unknown  among  the  Miocene  beds ;  and  of 
course  where  induration  exists  the  tawny  color  due  to  oxidation  penetrates 
to  a  much  smaller  depth  than  in  the  rocks  of  looser  texture.  Deep  brown, 
highly  ferruginous  sandstone  is  frequent  in  the  form  of  nodules,  as  are  sin- 
gle narrow  beds,  particularly  in  the  rocks  of  the  Chico-Tejon  group,  but  it 
seldom  or  never  occurs  in  large  masses.  The  sandstones  of  the  Knoxville 
(Neocomian)  group  are  in  great  part  metamorphosed,  and  they  give  rise  to 
the  series  of  rocks  which  will  be  discussed  in  the  following  pages.  The 
unaltered  Knoxville  sandstones,  on  the  other  hand,  lithologically  considered, 
do  not  materially  differ  from  those  of  subsequent  periods.  This  fact  is  not 
a  source  of  confusion  in  field  work,  however,  for  the  portion  of  the  Knox- 
ville sandstones  which  has  entirely  escaped  alteration  is  small,  and,  so  far 
as  observed,  these  are  associated  with  greatly  disturbed  and  intensely  met- 
amorphosed rocks  of  the  same  period  in  such  a  way  as  to  leave  no  doubt 
as  to  their  age  when  once  it  is  established,  as  will  be  done  in  a  succeeding 
chapter,  that  the  great  epoch  of  upheaval  and  of  rnetamorphism  in  the  Coast 
Ranges  preceded  the  Chico  and  Wallala  periods.  There  is  more  difficulty  in 
distinguishing  the  somewhat  altered  rocks  of  later  periods  from  similar  sand- 
stones of  the  Knoxville  group,  but  associated  silicification  and  serpentiniza- 
tion  appear  to  be  confined  to  beds  not  younger  than  the  Knoxville  series. 

Among  the  unaltered  rocks  impure  limestones  play  an  extremely  sub- 
ordinate but  still  important  part,  since  they  contain  the  best  fossils  of  the 
Knoxville  group.  More  widespread  are  shales  (sometimes  calcareous), 
which  form  a  connecting  link  between  the  sandstones  with  a  calcitic  cement 
and  the  limestones.  The  shales  and  limestones  together  form  but  a  small 
portion  of  the  entire  mass. 

origin  of  the  sandstone. —  It  is  found  that  the  unaltered  or  very  slightly  al- 
tered sandstones  of  all  ages  may  be  discussed  together  from  a  lithological 
point  of  view.  The  first  point  which  suggests  itself  for  consideration  is  the 
internal  evidence  of  their  origin  which  these  rocks  present.  One  of  the 
more  important  generalizations  resulting  from  the  field  study  of  the  quick- 
silver belt  is  that  granite  probably  underlies  the  entire  area  of  the  Coast 
Ranges.  This  inference  has  received  unexpectedly  strong  confirmation 
from  the  microscopical  study  of  the  sandstones,  for  the  entire  series  is  thus  • 


AECOSE.  61 

shown  to  be  composed  of  granitic  detritus,  or,  in  other  words,  to  be  arcose. 
In  many  cases,  indeed,  it  appears  from  structural  considerations  improb- 
able that  the  sands  were  immediately  derived  from  granite  and  altogether 
probable  that  they  were  formed  by  ftre~  disintegration  of  earlier  sand- 
stones. The  microscope  shows,  however,  that  some  of  these  rocks  consist 
of  grains  of  such  angularity  and  sharpness  as  to  lead  inevitably  to  the  con- 
clusion that  they  were  directly  derived  from  granites — indeed,  from  granites 
at  no  great  distance  from  the  point  of  deposition.  As  a  rule  the  grains  are 
worn  and  rounded  like  ordinary  beach  sand,  and  in  such  cases  the  micro- 
scope fails  to  show  whether  the  material  was  immediately  or  indirectly  de- 
rived from  the  original  granite.  But  the  arcose  character  is  persistent  in 
all  these  rocks,  and  this  points  to  short  transportation;  for  the  admirable  ex- 
periments and  observations  of  Mr.  Daubree  prove  that  the  feldspathic  con- 
stituents of  granite  are  rapidly  triturated  and  decomposed  in  running  water. 
I  cannot  recall  any  description  in  geological  literature  of  a  mass  of  arcose 
so  immense  as  that  exposed  in  the  Coast  Ranges. 

All  the  characteristic  components  of  granite  reappear  in  the  sandstones, 
often  in  proportions  differing  but  little  from  those  which  prevail  in  the 
parent  rock,  and  it  is  very  rarely  the  case  that  the  sandstones  contain  any 
clastic  fragments  or  allothigenetic  minerals  not  identified  in  the  granites 
still  exposed  in  the  Coast  Ranges.  Chemical  analysis  is  not  calculated  to 
exhibit  the  origin  of  the  sandstones,  for  in  the  course  of  disintegration 
and  transportation  a  certain  amount  of  material  must  have  been  reduced 
to  impalpable  powder,  decomposing  agencies  cannot  have  been  altogether 
absent,  and  a  certain  amount  of  mechanical  concentration  must  have  taken 
place,  although  this  last  influence  was  reduced  to  a  minimum  by  the  close 
approach  of  orthoclase  to  the  density  of  quartz.  It  is  manifest  that  the 
chemical  indifference  and  superior  hardness  of  the  quartz  establish  a  ten- 
dency to  greater  acidity  in  the  sandstones  than  in  the  granites. 

Microscopical  character. — The  quartz  of  the  fresh  and  of  the  slightly  decom- 
posed  sandstones  is  exactly  similar  to  that  of  the  granite  and  commonly 
contains  abundant  fluid  inclusions,  those  of  small  size  and  regular  form 
showing  active  bubbles.  The  feldspars  are  often  present  in  about  the  same 
quantities  as  the  quartz.  The  predominant  species  is  orthoclase,  with  char- 


62  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

acteristic  cleavages,  extinctions,  and  twinning.  Oligoclase  is  the  most 
abundant  triclinic  feldspar,  but  in  a  few  cases  angles  of  extinction  between 
20°  and  30°  on  each  side  of  the  twinning  plane  indicate  the  presence  of 
more  basic  species.  Biotite  is  also  a  constituent  frequent  in  many  of  the 
sandstones.  When  it  occurs  it  is  usually  allothigenetic,  and  this  is  shown 
by  its  relation  to  the  structure  of  the  mass,  the  scales  being  distorted  by 
the  pressure  of  the  unyielding  grains  of  quartz  and  feldspar  about  it.  Occa- 
sionally biotites  appear  to  have  been  bruised  edgewise  and  very  finely  di- 
vided clastic  material  has  silted  in  between  the  contorted  foils.  The  biotite 
when  fresh  is  dirty  brown  in  color  and  in  no  respect  differs  from  that  of  the 
granites.  That  a  white  mica,  probably  muscovite,  forms  in  the  sandstones 
epigenetically  from  biotite  is  certain.  It  is  also  found  in  such  a  way  as 
to  suggest  that  it  is  allothigenetic,  but  it  is  not  impossible  to  explain  these 
cases  by  epigenesis.  While  it  is  altogether  probable  on  general  principles 
that  the  muscovite  of  the  granite  is  represented  in  the  sandstone,  the  nature 
of  the  case  precludes  absolute  certainty  on  this  point.  Muscovite  is  a  very 
subordinate  constituent  of  the  granite. 

Hornblende,  exactly  like  the  granitic  hornblende,  is  tolerably  common 
in  the  sandstones,  usually  in  very  small  grains.  Titanite  in  rounded  grains, 
minute  zircons,  and  occasionally  epidote  have  been  observed.  A  strongly 
refracting,  monochroitic  mineral  was  detected,  which,  after  separation,  was 
proved  by  chemical  tests  to  be  rutile.  Tourmaline  in  large,  brown,  in- 
tensely dichroitic  grains  was  also  found  in  the  same  sandstone  as  the  rutile. 
Small  apatites,  especially  included  in  the  clastic  quartz  grains,  are  not  un- 
common in  the  sandstones.  Some  of  the  slides  of  granite  in  the  collection 
show  more  apatite  in  the  quartz  grains  than  do  any  of  the  slides  of  sand- 
stone, but  apatite  is  rather  irregularly  distributed  in  the  granite  and  some 
thin  sections  of  this  rock  contain  extremely  little  of  it. 

•/ 

The  only  allothigenetic  material  not  derivable  from  the  granite  which 
appears  with  any  considerable  frequency  consists  of  occasional  black  scales, 
sparsely  distributed. in  some  localities,  from  the  Knoxville  group  upwards. 
In  many  cases  these  scales  seem  referable  to  carbonaceous  shale ;  in  others 
they  at  least  suggest  plant  remains,  such  as  are  found  in  the  schists  of  the 
Knoxville  series. 


CHAEACTER  OF  METAMOEPHISM.  63 

Alteration  of  the  sandstones. — The  sandstones  have  been  changed,  under  the 
conditions  which  have  prevailed  in  the  Coast  Ranges,  by  several  distinct 
processes  of  varying  interest  and  importance.  They  are,  of  course,  sub- 
ject to  the  ordinary  decompositions  known  TIS  weathering.  Here  the  ferro- 
magnesian  silicates  are  in  part  converted  into  chlorite  and  in  part  also  into 
a  ferruginous  cement;  the  feldspars  become  carious,  while  the  quartz  is 
nearly  or  quite  unaffected.  Much  more  interesting  is  the  process  of  meta- 
somatic  recrystallization,  which  is  in  some  respects  the  inverse  of  weather- 
ing. In  rocks  which  have  undergone  this  process  the  clastic  grains  are 
transformed  into  ferromagnesian  silicates,  feldspar,  zoisite,  apatite,  etc.  A 
third  process  is  that  of  serpentinization.  This  sometimes  occurs  in  sand- 
stones in  which  metasomatic  recrystallization  has  either  not  taken  place  at 
all  or  only  to  an  insignificant  extent.  The  recrystallized  rocks,  however, 
are  also  subject  to  serpentinization,  and  from  them  the  greater  part  of  the 
serpentine  of  the  Coast  Ranges  appears  to  have  been  produced.  A  fourth 
process  is  silicification,  by  which  shales  have  been  converted  into  phthanites 
and  sandstones  into  quartzites.  The  serpentines  and  crystalline  metamor- 
phics  also  yield  to  a  similar  process  and  are  converted  into  a  dark,  opaline 
substance  known  in  some  of  the  quicksilver  mines  as  quicksilver  rock,  but 
this  seems  to  be  a  phenomenon  attending  the  process  of  ore  deposition 
rather  than  that  of  regional  metamorphism.  A  further  rather  unimportant 
process  manifests  itself  in  many  localities  by  the  presence  of  numerous 
stringers  of  calcite  or  gypsum  intersecting  the  rocks,  particularly  the  sand- 
stones, in  all  directions.  This  process  has  affected  many  of  the  younger 
rocks,  as  well  as  those  of  the  Neocomian. 

It  is  important  to  remark  that  some  of  these  processes  are  inconsistent 
with  one  another.  Evidently  chloritization  of  the  ferromagnesian  silicates 
cannot  go  on  simultaneously  with  the  formation  of  ferromagnesian  silicates 
by  metasomatic  recrystallization,  and  this  process  is  equally  inconsistent 
with  serpentinization.  So,  too,  since  serpentine  is  subject  to  conversion 
to  chalcedony,  serpentinization  and  silicification  must  go  on  under  different 
sets  of  conditions. 

weathering  of  the  sandstones. — The  weathering  of  the  sandstones  can  be  very 
briefly  disposed  of.  The  chlorite  which  forms  in  this  process  from  the 


64  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

ferromagnesian  silicates  appears  to  be  identical  with  that  which  results 
from  the  similar  minerals  of  the  recrystallized  rocks.  The  nature  of  this 
chlorite,  will  necessarily  be  discussed  in  connection  with  these  rocks.  Ser- 
pentine has  not  been  identified  with  certainty  among  the  results  of  weath- 
ering in  these  sandstones.  It  is  possible,  however,  that  it  forms  a  very 
subordinate  product  of  this  process.  The  decomposition  of  the  feldspars 
calls  for  no  special  comment,  excepting  that  there  is  no  considerable  quan- 
tity cf  well  marked  kaolin. 

CONCRETIONS. 

Analysis  of  an  example. —  One  of  the  most  interesting  changes  which  take 
place  in  the  sandstones  is  the  formation  of  concretions.  These  are  very 
common  in  the  Chico-Tcjon  and  Miocene  groups.  That  they  really  repre- 
sent changes  of  composition  within  the  rock  mass  is  certain,  for  they  often 
develop  into  a  symmetrical,  spheroidal  shape,  without  disturbance  of  the 
stratification,  which  the  formation  of  concretions  does  not  wholly  obliterate. 
That  these  concretions  could  not  gradually  be  built  up  during  sedimenta- 
tion is  certain.  They  are  usually  much  harder  than  the  surrounding  rock, 
darker,  and  of  a  redder  color.  In  a  great  majority  of  cases  no  nucleus  can 
be  found  at  the  center.  Under  the  microscope  the  chief  peculiarity  of 
these  concretions  was  found  to  consist  in  a  brown  cement  between  the 
clastic  fragments  of  granitic  origin.  This  cement  does  not  effervesce  with 
acid  and  is  so  unusual  in  character  as  to  call  for  investigation. 

A  concretion  from  the  Chico  beds  of  New  Idria  (No.  53)  was  selected 
for  examination.  One  sample  of  the  pulverized  rock  was  treated  with  cold, 
dilute  chlorhydric  acid  (1:10)  and  the  resulting  solution  analyzed.  Another 
sample  was  digested  with  stronger  acid  (1:1),  at  first  at  ordinary  tempera- 
tures and  then  for  twenty-four  hours  on  the  water-bath.  The  solution 
formed  was  analyzed  and  the  residue  was  treated  with  a  hot  solution  of 
sodic  carbonate  to  extract  soluble  silica.  Special  determinations  were 
made  of.  carbonic  acid,  feiric  oxide,  etc.  The  following  table  shows  the 
percentages  soluble  in  weak  acid  and  in  strong  acid  separately. 


CONCRETIONS  IN  SANDSTONES. 


05 


X 

First 
sample. 

Second 
sample. 

Loss  at  100°  n30 

0  855 

Carbonic  anhydride  CO7  

8.952 

Silica  SiO?            

0.362 

0.177 

Phosphoric  acid  P'-O*      

0.034 

0.035 

0.320 

0.385 

Ferric  oxide  Fe'O* 

0  607 

0.783 

0  195 

0  162 

11  152 

0  139 

0.315 

0.  162 

Soda  Na2O                 .                    

0  031 

0.122 

Potassa  K2O                             -                  

0  068 

0  119 

Silica  extracted  by  Na2C03  

2.865 

72  110 

99  956 

When  the  atomic  ratios  of  this  analysis  are  calculated  it  appears  that 
the  protoxide  bases  found  in  the  first  sample  are  slightly  in  excess  of  the 
amount  required  to  saturate  the  carbonic  acid.  All  excess  of  these  bases, 
as  well  as  the  alumina  and  the  iron  (which  is  wholly  in  the  ferric  state), 
must  be  combined  with  phosphoric  and  silicic  acids.  Assuming  that  the 
phosphorus  is  as  usual  combined  as  triphosphate  of  calcium,  the  remainder 
is  a  silicate  or  a  mixture  of  silicates.  The  atomic  ratio  of  the  sum  of  these 
silicates  is: 

Si  :  ft"  :  R"  0.22688  :  0.09385  :  0.22695 

or  Si  :  ft"  :  R"  5:2:  5. 

If  the  water  is  taken  into  account,  as  it  apparently  should  be,  the  ratio 
becomes  2:5:2:5,  indicating  some  form  of  a  hydrous  subsilicate. 

The  cementing  material  of  the  concretion  then  is  an  intimate  mixture 
of  calcium  carbonate  with  a  hydrous  subsilicate  and  a  small  but  not  incon- 
siderable amount  of  phosphate.  The  subsilicate  may  probably  be  regarded 
as  an  iron  compound  in  which  a  portion  of  the  iron  is  replaced  by  alumina 
and  protoxide  bases.  How  such  a  cement  can  be  formed  within  the  body 
of  a  sandstone  is  evidently  a  question  of  great  interest,  and  in  its  answer 
lies  the  secret  of  the  class  of  concretions  of  which  the  specimen  investi- 
gated is  an  example. 

Action  of  a  nucleus. —  Since  it  is  manifestly  impossible  that  these  concretions 
should  be  built  up  during  the  deposition  of  the  sand,  they  must  be  due  to 


MON   XIII- 


66  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  action  of  some  substance  embedded  in  the  rock.  The  spherical  form 
which  they  tend  to  assume  and  to  which  they  often  closely  approximate 
indicates  that  this  substance  either  exists  or  once  existed  at  the  center,  and 
this  simple  inference  is  confirmed  by  the  fact  that  the  concretions  are  often 
separable  into  spherical  shells,  indicating  a  change  in  composition  related 
to  the  distance  from  the  center.  Such  concretions  are  common,  for  exam- 
ple, in  the  Chico  beds  near  Lower  Lake.  So  far  as  my  observation  goes, 
the  central  substance  has  utterly  disappeared  in  a  great  majority  of  cases. 
In  three  or  four  instances  I  have  found  fossils  at  the  centers  of  these  con- 
cretions, but  I  have  broken  open  great  numbers  of  them  without  finding 
any  visible  difference  in  the  substance  at  the  center  and  elsewhere.  Such 
was  the  case  in  the  specimen  investigated,  and  chemical  tests  also  failed  to 
detect  any  foreign  substance.  Thus,  while  fossils  are  occasionally  found 
both  in  California  and  elsewhere  at  the  centers  of  concretions  in  sandstone, 
such  cases  are  so  rare  that  one  would  by  no  means  be  justified  from  obser- 
vation in  ascribing  the  concretions  to  the  action  of  organic  matter,  nor  am 
I  aware  that  it  has  ever  been  shown  how  organic  matter  could  effect  such  a 
result. 

Nucleus  possibly  organic. —  The  analysis  given  above  appears  to  me  capable 
of  interpretation  in  a  manner  calculated  to  throw  light  on  the  nature  of  the 
central  substance.  The  cement  of  the  concretion  contains  one-fourth  of  1 
per  cent,  of  phosphoric  acid,  most  of  which  must  have  come  from  the  cen- 
tral substance,  for  the  cement  of  the  sandstone  away  from  concretions  is 
almost  pure  calcite.  Taking  the  size  of  the  concretions  into  account  this 
indicates  the  existence  of  much  phosphorus  in  the  central  substance.  The 
possibly  organic  nature  of  the  substance  in  question  is  thus  strongly  sug- 
gested. But  is  there  any  way  in  which  an  organic  substance  could  give 
rise  to  the  formation  of  hydrous  ferric  silicate?  I  think  there  is. 

It  is  well  known  that  during  the  decomposition  of  organic  matter 
various  acids  are  formed,  and  that  among  them  the  group  of  humus  acids 
frequently  occurs.  These  acids,  or  some  of  them,  dissolve  magnetite,  and 
in  this  way  sands  underlying  vegetable  soils  are  frequently  bleached.' 

'Kolli:   Alljj;.   uml  rlirm.  Geol.,  vol.  1,  j>.  &9o;  and    A.  A.  J alien  :  On   tlm  geological   action  of  ihr 
hunins  ;u-i(ls,  Proc.  Am.  Assoc.  Ailv.  Sci.,  vol.  2$,  1879,  JIM.  311-410. 


CONCRETIONS  IN  SANDSTONES.  67 

Some  of  these  acids  also  combine  with  silica  to  silico-azo-lmniic  acids. 
According  to  Mr.  P.  Thenard,  acids  of  this  series  form  spontaneously  in  the 
soil  from  humic  acid,  the  ammonia  of  rain  water,  the  nitrogen  of  the  air, 
and  the  silica  contained  in  the  soil. 

Modus  operands. —  It  is  clear  that  a  fragment  of  undecom posed  organic  mat- 
ter embedded  in  a  porous  sandstone  may  decompose  under  the  action  of 
percolating  surface  waters  and  that  under  favorable  conditions  it  may  yield 
humic  acid  which  will  attack  the  magnetite,  always  present  in  greater  or 
smaller  quantity.  With  the  silica  of  the  rock  silico-azo-humic  acid  may 
also  be  produced.  Were  large  quantities  of  organic  matter  present  to- 
gether with  much  water  the  result  might  be  a  mere  bleaching  of  the  sand- 
stone; but,  if  small  quantities  of  the  solutions  of  the  humic  compounds  only 
are  formed,  they  will  be  drawn  into  the  surrounding  sandstone  by  capillary 
action  and  a  more  or  less  nearly  spherical  mass  will  be  impregnated  with 
them.  This  mass  may,  perhaps,  increase  in  size  until  the  organic  matter  is 
exhausted. 

The  humic  compounds  are  very  unstable,  and  a  globular  mass,  such 
as  is  supposed  above,  would  soon  decompose  into  carbonic  acid,  water,  etc. 
There  would  then  remain  a  spheroidal  mass  of  carbonates  and  silicates  of 
the  bases  which  had  been  dissolved  at  an  earlier  stage.  The  latter  being 
formed  at  low  temperatures  would  not  improbably  be  hydrous.  Calcium 
phosphate  is  soluble  in  solutions  of  carbonic  acid,  and  one  would  therefore 
expect  to  find  the  phosphorus  of  the  organic  substance  also  diffused  through 
the  mass.  The  hypothesis  of  a  decomposing  organic  nucleus  thus  appears 
to  account  in  a  rational  manner  for  all  the  observed  facts. 

summary  of  evidence. — The  fossils  occasionally  met  with  in  sandstone  con- 
cretions are  so  rare  as  only  to  suggest  that  these  masses  may  have  been 
indurated  through  the  indirect  action  of  organic  matter.  The  presence  of 
phosphoric  acid  in  notable  quantities  in  the. matrix  of  concretions  which 
contain  no  fossils  greatly  strengthens  the  hypothesis  that  organic  matter 
once  existed  in  these  masses,  but  has  since  disappeared.  When  it  is  found 
that  the  chemical  character  of  the  matrix  of  these  concretions  is  also  such  as 
would  result  from  the  decomposition  of  organic  matter  by  processes  of  which 
the  main  features  are  well  known,  the  weight  of  the  concurrent  evidence  is 


68  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

very  great.  It  is  clear  that  the  formation  of  concretions  is  due  to  the  pres- 
ence of  small  masses  of  some  foreign  substance  in  the  sandstone.  Were 
this  substance  composed  of  any  other  elements  than  carbon,  hydrogen, 
nitrogen,  and  phosphorus,  such  elements  would  almost  inevitably  appear  as 

y:omponents  of  the  concretion.  It  thus  appears  to  me  nearly  certain  that 
he  concretions  are  due  to  the  action  of  decomposition-products  arising 
rom  organic  matter. 

It  is  evident  that  the  formation  of  concretions  by  means  of  organic 
matter,  as  sketched  above,  is  a  result  which  will  take  place  only  under  some- 
what special  conditions.  If  sufficient  organic  matter  exists  in  a  rock,  indu- 
ration of  the  entire  mass  may  occur.  If  the  huinic  components  are  washed 
through  the  rock  without  being  allowed  to  decompose,  the  rock  will  be 
bleached.  Both  of  these  last  cases  are  considered  by  Professor  Julien  in 
the  paper  referred  to  above,  but  he  does  not  particularly  discuss  the  subject 
of  concretions 

NODULES    RESULTING   FROM    EXTERNAL    ATTACK. 

cases  to  be  discussed. — Besides  the  concretions  discussed  above,  rounded  nod- 
ules are  found  in  many  decomposing  rocks.  In  the  present  memoir  such 
occurrences  will  be  noted  in  the  basalts  of  the  Sulphur  Bank  mine  and  in 
the  partially  serpentinized  rocks,  especially  near  Knoxville,  Napa  County. 
They  are  also  well  known  to  occur  in  some  decomposed  granites  and  in  an- 
desites,  those  for  instance  near  the  Comstock  lode.  The  principles  on  which 
they  are  formed  are  extremely  simple,  but,  so  far  as  I  know,  they  have  never 
been  stated,  and  a  lack  of  knowledge  of  them  has  often  led  to  erroneous 
assumptions  of  a  mysterious  ball  structure  in  the  rocks  which  favors  such 
decomposition.  As  will  be  seen  below,  pebbles  in  brooks  and  on  beaches, 
as  well  as  grains  of  sand,  are  rounded  in  a  manner  closely  analogous. 

Deduction  of  relations. — Suppose  a  sphere  of  any  homogeneous  substance, 
into  which  liquids  can  penetrate  a  small  but  finite  distance,  and  let  this  dis- 
tance be  assumed  as  the  unit  of  length.  Then,  if  r  is  the  radius  of  the 
sphere,  the  volume  of  the  solid  which  can  be  permeated  by  a  liquid  acting 
on  the  exterior  is  a  spherical  shell,  the  content  of  which  is : 

V  =  J  it  >'3-*  n  (r-l)s  =  j  n  (3r! 


NODULES.  69 


The  surface  of  the  sphere  is,  say,  S=:4  ir  r2  and 


The  surface  of  the  material  exposed  to  the  action  of  the  fluid  per  unit 
of  volume  of  the  shell  acted  upon,  orS/V,  may  readily  be  seen  from  this 
equation  to  diminish  rapidly  as  the  radius  of  the  sphere  increases.1  For 
example,  if  the  radius  is  unity,  or  just  equal  to  the  depth  to  which  the 
solid  is  permeable,  S/V  =  3;  if  r=2,  S/  V  =  1.7  ;  if  r  =4,  S/V=1.3,  and 
if  the  radius  is  infinite  or  if  the  attacked  surface  is  flat,  S/'Vz=l. 

Suppose  a  unit  of  volume  of  a  thoroughly  porous,  solid  substance  in 

any  given  shape  and  exposed  to  the  action  of  a  solvent  liquid:  the  liquid 

will  become  partially  saturated  near  the  surface  of  the  solid  and  will  act 

less  vigorously  upon  the  underlying  portions.    It  is  clear,  therefore,  that,  if 

the  body  is  given  the  shape  of  a  slender  rod  and  is  acted  upon  by  the  fluid 

from  one  end  only,  it  will  dissolve  less  rapidly  than  it  would  if  the  same 

mass  were  formed  into  a  thin  sheet  and  were  attacked  over  the  whole  of 

''one  surface  of  this  sheet.     It  is  easy  to  see  that  the  rate  at  which  solution 

will  take  place  in  this  case  is  nearly  proportional  to  the  surface  exposed  to 

jlie  action  of  the  fluid. 

Hence  it  is  sufficiently  accurate  for  the  present  purpose  to  assume  that 
the  rate  at  which  a  spherical  mass  will  be  attacked  by  a  corrosive  fluid  will 
be  proportional  to  the  surface  exposed  per  unit  of  volume  of  the  permeable 
shell,  or  to  S/V.  This  function  (and  therefore,  also,  the  rate  at  which  so- 
lution will  take  place),  as  has  been  shown  above,  varies  in  a  certain  inverse 
ratio  to  the  radius  of  the  sphere.2 

If,  therefore,  any  comparatively  dense,  irregular  body  is  acted  upon 
by  solvent  or  decomposing  solutions,  the  portions  the  radii  of  curvature 

1  The  portion  of  the  sphere  which  is  not  reached  hy  the  fluid  is  essentially  a  positive  quantity,  and 

4 
when  /•  becomes  less  than  unity,-  n  (>'  —  I)3  disappears  from  the   value  of  S/V,  which  thus  becomes 

9 

equal  to  3/r.  This  is  a  hyperbola,  asymptotic  to  both  axes,  and  S/V  is  in  Unite-  fon-  =  0.  At  the  point 
at  which  »•  =  1  this  hyperbola  passes  over  into  the  curve  of  the  third  degree  given  in  the  text.  The 
hyperbola  would  be  asymptotic  to  S/V  =  0,  while  the  higher  curve  is  asymptotic  to  S/V  =  1. 

2  This  conclusion  is  not  affected  by  the  uncertainty  which  exists  as  to  the  exact  function  represent- 
ing the  rate  of  solution  in  terms  of  S/V  ;  for  it  is  clear  that  in  any  ease  this  function  and  S/V  must 
vary  directly,  and  that  both  of  tlicin,  therefore,  vary  invcrsrlj  as  the  radius  of  curvature. 


70  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPK. 

of  which  are  equal  to  or  less  than  the  distance  to  which  the  fluid  can  per- 
meate will  yield  very  rapidly,  while  those  of  less  abrupt  curvature  will  he 
more  slowly  decomposed  or  dissolved.  There  will  thus  he  a  constant  tend- 
ency to  diminish  the  curvature  of  the  more  salient  portions  and,  if  the  mass 
is  not  too  thin,  to  reduce  it  to  a  sphere. 

cases. — Two  special  cases  need  consideration:  If  the  action  of  the  fluid 
were  strictly  confined  to  the  surface  or  if  the  mass  were  absolutely  imper- 
meable, the  radius  of  curvature  would  always  be  infinite  compared  with  the 
distance  to  which  a  fluid  could  penetrate,  and,  if  solution  took  place,  the 
mass  would  always  retain  an  angular  form,  the  surfaces  of  which  would  be 
parallel  to  those  which  it  originally  presented.  On  the  other  hand,  if  the 
fluid  could  permeate  to  the  center  of  the  body,  all  portions  would  be 
attacked  at  once  and  it  would  disintegrate  almost  .simultaneously  through- 
out its  mass. 

Nearly  every  American  has  daily  opportunities  for  observing  the  rela- 
tions here  reduced  to  exact  terms.  Clear,  solid  ice  is  practically  imperme- 
able by  water,  and  an  angular  fragment  of  such  ice  in  a  glass  of  water 
becomes  only  slightly  rounded,  while  the  surfaces  at  all  stages  of  the 
melting  process  are  nearly  parallel  to  the  original  ones.  On  the  other 
hand,  a  bit  of  ice  which  is  clouded  with  small  air  bubbles  is  permeable  by 
water  to  the  depth  of  these  bubbles,  and  consequently  the  edges  and  cor- 
ners of  an  angular  mass  of  such  ice  are  quickly  rounded.  Again,  a  lump 
of  cane  sugar  is  very  porous  and  fluids  permeate  to  its  center.  It  there- 
fore disintegrates  under  the  action  of  a  solvent  fluid  almost  without  pre- 
liminary rounding  of  the  edges  and  corners. 

Application  to  decomposing  rocks. — The  behavior  of  rocks  to  dissolving  or  decom- 
posing  agencies  is  similar.  There  do  not  seem  to  be  any  rocks,  excepting 
perhaps  some  obsidians,  which  are  permeable  only  to  an  insensible  distance 
by  fluids ;  but  there  are  many  rocks  so  dense  that  fluids  penetrate  them 
with  great  difficulty  and  very  slowly.  In  such  cases  the  corrosive  reagents 
which  waters  contain  are  neutralized  by  the  time  the  solutions  have  pene- 
trated to  a  very  small  depth,  and  corrosive  action  is  limited  to  this  thin  outer 
layer  As  decomposition  is  completed  in  the  outer  layer,  active  reagents 
will  of  course  permeate  farther  and  farther  into  the  rock.  The  geometrical 


71 

results  will  clearly  be  those  discussed  above.  An  angular  mass  of  such  a 
rock  will  yield  to  the  decomposing  agencies  directly  as  S/\r,  or  in  an 
inverse  ratio  to  its  radius  of  curvature,  and,  if  the  mass  is  homogeneous,  it 
will  gradually  be  reduced  to  the  spherical-  form.  It  thus  becomes  evident 
that  angular  blocks  of  basalt  attacked  by  sulphuric  acid  or  other  corrosive 
fluids  tend  to  the  spherical  form,  not  because  of  any  variation  in  the  internal 
structure,  but,  on  the  contrary,  because  they  are  substantially  homogeneous. 

The  rocks  which  do  not  weather  or  decompose  to  rounded  masses  are 
the  more  permeable  class.  Thus,  in  the  Washoe  district  dense  andesites  and 
basalts  tend  to  the  spherical  form,  Avhile  tufaceous  masses  and  porous  rocks 
decompose  Avith  tolerable  uniformity  throughout.  In  terms  of  the  mathe- 
matical discussion  for  the  latter,  r  <  1.  Just  so  along  the  quicksilver  belt: 
dense  rocks  undergoing  serpentinization  show  rounded  nodules  of  unaltered 
or  slightly  altered  material,  while  more  permeable  masses  are  gradually 
changed  to  serpentine  throughout. 

It  may  not  be  amiss  to  note  that  the  depth  to  which  a  rock  will  be  at- 
tacked by  any  decomposing  fluid  depends  somewhat  upon  the  nature  of  the 
fluid.  If  the  reaction  between  the  liquid  and  the  solid  is  a  rapid  one  the 
liquid  will  become  substantially  saturated  comparatively  near  the  surface, 
while,  if  the  reaction  is  feeble  and  slow,  the  fluid  Avill  penetrate  to  a  greater 
depth  before  losing  its  corrosive  power.  Complex  cases  sometimes  result 
from  the  co  existence  of  various  reactions,  each  leading  to  a  particular  kind 
of  decomposition. 

Application  to  pebbles. —  It  is  evident  that  the  principles  applied  in  the  fore- 
going discussion  are  not  limited  to  the  action  of  fluids.  Any  disintegrating 
agency  acting  uniformly  on  the  surface  of  an  angular  body  or  acting  suc- 
cessively on  all  points  of  its  surface  Avill  be  governed  by  similar  laws. 
Consider  a  fragment  of  rock  in  a  stream  bed  or  on  a  beach.  It  suffers 
frequent  impacts  from  other  bodies  of  similar  average  size  and  composition. 
Each  of  these  impacts  disintegrates  the  mass  at  the  small  surface  of  contact 
to  a  certain  average  depth,  and  these  impacts  are  repeated  in  indefinite 
number  on  all  portions  of  its  surface.  The  result  must  be  the  same  as  if 
the  rock  fragment  were  subjected  to  a  disintegrating  action  simultaneously 
at  all  points  of  its  surface,  and,  just  as  in  the  case  of  a  solvent  fluid,  the 


72  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

mass  must  tend  to  a  spherical  form,  provided  tha,t  it  is  of  uniform  composi- 
tion. 

If  the  body  is  permeable  to  different  depths  in  different  directions  or 
if  it  offers  more  resistance  to  abrasion  in  one  direction  than  it  does  in  others, 
the  surfaces  which  offer  the  least  resistance  will  evidently  be  most  rapidly 
attacked.  Hence,  pebbles  of  sedimentary  rocks,  which  do  not  in  general 
possess  equal  coherence  in  all  directions,  will  not  tend  to  a  spherical  form, 
but  to  one  more  or  less  approaching  a  spheroid  or  even  an  ellipsoid. 

It  appears  from  the  literature  of  geology  that  rounded  masses  resulting 
from  the  decomposition  of  comparatively  impermeable  rocks  have  not 
infrequently  been  mistaken  for  water-worn  pebbles.  When  one  considers 
that  in  both  cases  the  approach  to  the  spherical  form  is  due  to  similar  causes 
this  does  not  e'.em  so  strange  as  it  otherwise  might. 

CEYSTALLINE    METAMOKPHIC    ROCKS. 

Groups  of  metamorphic  rocks. — The  metamorphosed  rocks  of  the  Coast  .Ranges 
may  be  divided  into  serpentine  and  a  more  or  less  crystalline  series.  The 
latter,  indeed,  usually  contain  some  serpentine  ;  but  serperitinization  is  evi- 
dently in  part  a  secondary  process  and  will  be  discussed,  together  with  the 
massive  serpentines,  in  a  succeeding  section.  The  division  of  the  crystal- 
line series  which  appears  best  to  satisfy  both  their  microscopical  charac- 
ter and  their  field  occurrence  is  as  follows :  (1)  Partially  metamorphosed 
sandstones,  in  which,  although  a  process  of  recrystallization  has  begun,  the 
clastic  structure  as  seen  under  the  microscope  is  not  obliterated,  though 
more  or  less  obscured.  These  rocks  will  be  referred  to  hereafter,  for  the 
sake  of  brevity,  as  altered  sandstones.  (2)  Granular  metamorphics,  in  which 
thorough  metasomatic  recrystallization  of  the  sandstones  has  transformed 
the  mass  into  a  granular,  holocrystalline  aggregate  which,  in  its  most  com- 
plex development,  consists  of  augite,  amphibole,  feldspar,  zoisite,  and 
quartz,  with  accessory  minerals.  This  class  cannot  be  sharply  separated 
from  the  first  or  from  the  following,  but  it  forms  a  natural  group,  one  or 
several  of  the  constituents  of  which  may  be  suppressed,  forming  different 
varieties  within  the  group.  (3)  Glaucophane  schist  of  an  origin  similar  to 
that  of  the  granular  rocks,  usually  carrying  mica,  quartz,  and  other  minerals. 


GROUPS  OF  METAMOKPI1IO  ROCKS.  73 

(4)  Phthanites  or  schistose  rocks  which  have  been  subjected  to  a  process 
of  silicification. 

There  is  seldom  any  doubt  about  the  rnacroscopical  determination  of 
the  third  and  fourth  of  these  groups  ;  in-a,  large  proportion  of  cases  also,  the 
granular  rocks  can  readily  be  distinguished  from  the  altered  sandstones 
with  the  naked  eye  or  the  loupe,  but  this  is  by  no  means  always  possible. 
Many  rocks  which  to  the  naked  eye  appear  to  be  merely  considerably 
altered  but  perfectly  recognizable  sandstones  turn  out,  upon  microscopical 
examination,  to  be  holocrystalline  and  to  have  lost  entirely  the  character- 
istic clastic  structure. 

The  granular  rocks  are  separable,  under  the  microscope,  into  several 
varieties,  according  to  their  mineralogical  composition ;  but  it  is  seldom 
possible  to  distinguish  these  varieties  macroscopically.  In  dealing  with 
eruptive  rocks  the  eye  soon  accustoms  itself  to  the  perception  of  very 
minute  differences  of  appearance  which  represent  or  are  associated  with 
microscopical  peculiarities.  The  metamorphic  rocks  are  physically  and 
chemically  much  more  heterogeneous  than  eruptives,  and  it  is  only  in 
extreme  cases  that  the  habitus  is  characteristic  of  the  precise  mineralogical 
composition. 

As  will  appear  in  the  sequel,  the  altered  sandstones  and  the  granular 
rocks  form  a  series  which  is  in  reality  unbroken.  The  processes  of  altera- 
tion can  be  studied  in  rocks  retaining  as  clearly  as  possible  evidences  of 
their  clastic  character.  The  same  processes  can  be  traced  through  series  in 
which  the  clastic  elements  gradually  disappear  and  in  the  extreme  members 
of  which  a  holocrystalline  mass  of  authigenetic  minerals  is  presented.  In 
the  altered  sandstones  various  transformations  begin  simultaneously,  and, 
according  to  the  physical  and  chemical  conditions  under  which  the  meta- 
morphism  occurred,  one  or  other  of  these  changes  may  predominate  in  the 
fully  altered  rock.  In  this  way  types  are  produced  so  distinct  that  were 
these  alone  submitted  to  examination  little  analogy  would  be  perceived 
between  them ;  but  they  are,  in  fact,  connected  with  one  another,  as  well 
as  with  the  unaltered  sedimentary  rpcks,  by  very  gradual  transitions. 

In  describing  the  various  types  more  or  less  repetition  is  unavoidable. 
For  the  sake  of  brevity  it  seems  expedient  to  begin  the  discussion  of  the 


74  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

rocks  by  noting  the  minerals  which  result  from  the  metamorphic  processes 
one  by  one,  leaving  for  subsequent  discussion  the  various  combinations  in 
which  they  occur. 

Biotite. — When  foils  of  biotite  are  compressed  into  zigzag  outlines  by  the 
pressure  of  adjacent  clastic  grains  the  mineral  is  evidently  allothigenetic. 
In  some  other  cases  there  is  a  lack  of  decisive  proof  as  to  the  origin  of  the 
biotite,  but  there  are  also  occurrences  which  can  only  be  interpreted  as  au- 
thigenetic.  The  authigenetic  biotite  scales  are  sharper  in  outline  than  the 
allothigenetic  foils,  and  are  usually  of  a  light,  clear,  chestnut-brown  color. 
In  cross-section  they  are  often  seen  to  be  undulous,  but  do  not  form  broken 
lines  like  clastic  foils.  They  are  frequently  embedded  in  recrystallizing 
feldspar  grains.  The  quantity  of  this  mica  detected  is  small,  and  it  seems 
probable  that  when  formed  it  readily  passes  over  into  white  mica  by  epi- 
genesis.  In  one  glaucophaue  schist  from  New  Idria  there  is  a  great  abun- 
dance of  fine,  nearly  uniaxial  biotite. 

Muscovite. — The  epigenetic  formation  of  white  mica  from  biotrteand  from 
feldspar  has  long  been  recognized.  In  the  recrystallizing  sandstones  of  the 
Coast  Ranges  white  mica  is  rather  rare  as  an  indubitably  allothigenetic  com- 
ponent, but  is  very  common  as  an  alteration  product  of  brown  mica.  It  also 
appears  to  form  in  the  cementing  mass  of  fine  detritus  and  deposits  between 
the  clastic  grains  of  sandstones;  but,  while  the  occurrences  and  the  analogies 
are  such  as  to  warrant  an  opinion  that  such  foils  of  white  mica  are  authi- 
genetic or  epigenetic  on  authigenetic  biotite,  it  can  hardly  be  demonstrated 
that  this  material  is  not  allothigenetic.  In  the  more  altered  rocks  it  is  seen 
forming  in  disintegrating  feldspar  grains  and  it  is  an  important  constituent 
of  the  glaucophane  schists.  Where  it  can  be  separated  in  foils  it  is  found 
that  the  angle  of  the  optical  axes  is  large. 

Augite. — Though  a  careful  watch  has  been  kept  for  rhombic  pyroxene, 
none  has  thus  far  been  detected  in  any  of  the  nietamorphic  rocks.  In  the 
rocks  which  retain  an  unmistakably  clastic  structure  augite  is  rare,  a  fact 
which  appears  to  be  due  to  the  tendency  of  the  mineral  to  decomposition 
when  the  structure  of  the  rock  in  which  it  exists  is  sufficiently  open  to  permit 
of  the  free  percolation  of  solutions.  There  are  a  few  examples,  however, 
which  leave  no  doubt  as  to  the  fact  of  the  formation  of  augite  in  sandstones 


COMPONENT  MES'EKALS.  75 

undergoing  the  process  of  metasomatic  recrystal-lization,  and  which  thus  form 
a  link  between  typical  sandstones  and  the  more  highly  altered  rocks  in  which 
the  clastic  origin  is  not  evident  on  mere  inspection.  In  these  rocks  minute 
bacillar  augitcs  make  their  appearance  irt  newly  formed  aggregates  limited 
by  the  outlines  of  the  original  clastic  grains.  There  is  clearly  a  tendency 
to  parallelism  and  to  grouping  of  these  augite  crystallites,  and  the  evidence 
points  irresistibly  to  the  conclusion  that  under  favorable  circumstances  large 
solid  crystals  of  augite  form  by  the  union  of  these  smaller  masses.  In  a 
considerable  number  of  instances  these  microlites  are  actually  united  in  close 
groups  bounded  by  crystallographic  outlines.  The  usual  occurrence  of  gar- 
net in  metamorphic  rocks  indicates  an  entirely  similar  process  of  aggrega- 
tion. It  is  quite  impossible  to  ascribe  any  but  an  authigenetic  origin  to 
these  characteristic  occurrences  of  augite  in  newly  formed  aggregates  arising 
from  the  alteration  of  clastic  grains,  nor  is  such  a  formation  surprising,  since 
the  artificial  reproduction  of  augite  by  the  action  of  heated  water  under 
pressure  upon  appropriate  mineral  mixtures  is  a  well  known  phenomenon. 
A  fine  example  of  a  partially  formed  augite  crystal  in  an  altered  sandstone  is 
shown  in  Fig.  2,  page  88. 

In  the  more  fully  crystallized  metamorphic  rocks  augite  is  often  very 
abundant.  It  is  of  lighter  tint  under  the  microscope  than  the  ordinary 
bamboo-colored  augites  of  eruptive  rocks,  is  monochroitic,  and  extinguishes 
at  high  angles.  It  readily  passes  over  into  uralite,  chlorite,  epidote,  and  ser- 
pentine. The  uralite  often  has  a  bluish  tint  approaching  that  of  glaucophane. 
There  is  a  marked  tendency  in  the  larger  augite  crystals  to  the  development 
of  the  orthopinacoidal  cleavage,  and  in  a  few  of  the  rocks  the  pyroxene  is 
well  developed  diallage. 

Hornblende — This  mineral  occurs  in  the  recrystallized  and  recrystallizing 
rocks  in  two  forms.  Brown  hornblende  forms  much  in  the  same  way  as 
augite  and  is  observed  sometimes  in  the  same  slides  with  it.  Groups  of 
hornblende  microlites  also  show  common  crystallographic  outlines;  a  case 
of  this  kind  is  shown  in  Fig.  3,  page  89. 

Either  minute  chemical  differences  or  certain  physical  conditions  seem 
to  regulate  the  preponderance  of  the  one  mineral  over  the  other,  so  that  the 
fully  recrystallized  rocks  are  divisible  with  some  sharpness  into  horriblendic 


76  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

and  augitic  groups.  No  clear  indication  has  been  detected  that  the  mode 
of  occurrence  differs  for  the  two  classes.  This  may  nevertheless  ba  the 
case,  for  the  amphibolic  and  pyroxenic  rocks  are  macroscopically  indis- 
tinguishable, excepting  in  a  few  cases,  and  differences  in  occurrence  would 
thus  readily  escape  detection.  At  present  it  seems  more  likely  that  the 
controlling  factor  is  an  unknown  and  certainly  very  slight  difference  of 
chemical  composition.  Observation  has  shown  me  that  it  is  absolutely 
necessary  in  some  eruptive  rocks  to  resort  to  a  chemical  explanation  of  the 
replacement  of  one  of  these  minerals  by  the  other  without  affecting  the 
probability,  in  another  class  of  instances,  that  the  same  replacement  is  due 
to  differences  of  physical  condition.1 

Green  hornblende  is  also  very  abundant.  Much  of  this  is  certainly 
uralitic  and  some  of  it  appears  probably  due  to  the  alteration  of  brown 
hornblende.  There  are  also  cases  in  which  the  green  hornblende,  so  far  as 
can  be  judged,  is  a  direct  product  of  metasomatic  action,  but  none  in  which 
every  other  explanation  is  excluded.  There  are  further  instances  which 
suggest  the  existence  of  a  brown  nralite,  btit  these  cases  are  believed  to  be 
better  explained  by  envelopment. 

The  authigenetic  hornblendes  are  readily  distinguished  from  allothi- 
genetic  fragments,  the  latter  being  commonly  of  a  dark,  dirty-green  color 
and  much  more  pleochroitic  than  the  newly  formed  mineral.  The  outline 
of  clastic  fragments  is  usually  characteristic.  In  extreme  cases  there  is  some 
difficulty  in  distinguishing  green  hornblende  from  chlorite,  but  where  the 
particles  are  not  excessively  minute  the  oblique  extinction  of  the  former  is 
generally  perceptible. 

oiaucophane. — This  is  a  prominent  component  of  the  micaceous  schists2 
and  occurs  also  in  the  more  composite  granular  rocks  and  in  the  amphibo- 
lite.  Cross-sections  frequently  show  the  amphibolic  outline  and  cleavage. 
The  pleochroism  and  absorption  are  strong.  The  pleochroic  colors  are  a, 
brownish  yellow  to  colorless;  1)>  violet;  c,  ultramarine  blue.  The  absorp- 

1  For  some  curious  evidence  bearing  on  this  point,  ECC  my  Geology  of  the  Comstock  Lodo  ami  ihe 
Washoe  District,  Mon.  U.  S.  Gcol.  Survey  No.  3,  p.  GO. 

'According  to  Mr.  H.  G.  Hanks,  glaucophane  was  detected  by  Mr.  Micbel-L<5vy,  in  1878,  in  speci- 
mens of  micaceous  schist  from  the  Wall  Street  quicksilver  mine,  Lake  County,  exhibited  at  the  Paris 
exposition  in  1878.  (Fourth  Annual  Report  of  the  State  Mineralogist  of  California,  1883-'84,  p.  182.) 


COMPONENT  MINERALS.  77 

tion  is  e>  i>  a.  The  angle  of  extinction  is  that  of  amphibole,  but  the 
interference  colors  are  of  lower  order.  The  specific  gravity  is  3.10  to  3.11,' 
but  the  mineral  is  visually  so  intimately  associated  with  others  as  to  make 
a  perfect  separation  difficult. 

The  genetic  relations  of  the  glaucophane  are  not  entirely  clear.  In 
the  greater  number  of  cases  it  is  closely  associated  with  ordinary  actinolite, 
and  there  appear  to  be  unquestionable  transitions  between  the  two.  Thus, 
one  portion  of  an  area  of  entirely  undecomposed  amphibole  of  uniform 
orientation  is  often  bright  blue,  another  green,  and  these  pronounced  tints 
shade  off  into  each  other  by  imperceptible  gradations.  Had  only  these  oc- 
currences been  observed,  the  conclusion  would  have  been  almost  inevita- 
ble that  the  two  varieties  of  amphibole  had  been  produced  simultaneously 
and  by  the  same  methods.  There  are  other  cases,  however,  in  which  nar- 
row streaks  of  the  blue  mineral  appear  along  the  junction  of  actinolite 
crystals,  which  suggest  the  possibility  of  epigenesis  of  glaucophane  upon 
actinolite.  I  am  inclined  to  consider  this  suggestion  misleading,  however, 
because  fibration  and  sensible  difference  of  orientation  would  almost  inev- 
itably result  from  such  a  process. 

zoiskc. — Much  the  most  interesting  mineral  yet  detected  in  the  rocks 
undergoing  metasomatic  recrystallization  is  zoisite,  which  as  an  important 
rock-forming  mineral  has  hitherto  been  observed  only  in  the  saussuritic 
crystalline  schists  and  gabbros.  In  the  rocks  of  the  Coast  Ranges  this 
mineral  is  one  of  the  first  indications  of  recrystallization;  it  is  found  in 
slides  of  every  group  of  the  recry  stall!  zed  rocks  and  is  often  present  in 
large  quantities,  especially  in  the  schists. 

The  zoisite  presents  no  good  cleavage,  but  traces  of  fissility  parallel 
to  the  main  axis  are  sometimes  visible.  The  prisms  are  usually  jointed  and 
terminal  faces  are  often  distinct.  Measurements  of  the  projection  of  the 
interfacial  angle  between  the  brachydome  and  brachypinacoid  agree  with 
the  real  value  of  this  angle  as  well  as  could  be  expected.  Square  cross-sec- 
tions are  not  uncommon  and  often  only  a  single  corner  appears  to  be  trun- 
cated. This  irregular  development  of  faces  in  the  vertical  zone  is  charac- 
teristic of  zoisite.2 


"Liideeko  found  the  spccilie  gravity  of  glaueophane,  from  Syra,  3.101  (Kotli:  All#.  mid  cliein.  Gool 
p.  21). 

-'  Pann's  System  of  Mineralogy,  p.  2DO. 


78 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


The  color  of  the  zoisite,  as  seen  by  the  naked  eye,  varies  from  gray  to 
deep  green.  In  the  former  case  it  is  of  course  colorless  in  thin  section,  and 
this  is  usually  the  case  in  the  augitic  and  hornblendic  rocks,  though  a  faint 
greenish  yellow  may  sometimes  be  observed.  In  the  glaucophane  rocks  the 
color  is  usually  deeper,  and  the  pleochroism  h  then  distinct  in  thin  section, 
c  being  yellowish  green  to  light  grass  green  and  a  and  l>  almost  colorless. 
The  absorption  is  hardly  perceptible.  The  pleochroism  increases  with  the 
thickness  of  the  section.  The  axes  of  elasticity,  when  their  position  can  be 
determined,  are  always  strictly  parallel  to  the  vertical  crystallographic  axis 
and  to  the  pinacoidal  faces.  The  angle  of  the  optical  axes  is  large  and  the 
plane  of  the  axes  is  parallel  to  one  of  the  pinacoidal  faces.  The  colors  of 
interference  usually  range  between  a  bluish  gray  and  a  pale  yellow,  but  are 
occasionally  more  vivid.  The  intensity  of  the  colors  often  seems  to  vary 
considerably  with  the  state  of  aggregation. 

Zoisite  occurs  in  the  phthanites  as  well  as  in  the  other  metamorphic 
rocks,  biit  usually  in  much  longer  needles  than  in  the  other  metamorphic 
rocks.  Fig.  1  shows  both  types  of  crystals,  between  which  there  are  plenty 
of  intermediate  forms. 


Tic;.  1.  7-oiaite  ivicroliles,  a,  6,  ami  c,  from  a  glaucophane  rock, No.  31,  Sulphur  ISii'.k.    a  and  I  arc  magnified  175  diameters; 
c,  ICG  diameters ;  d  is  from  minute  quartz  veins  in  phlbanite  (Xo.  51,  Mt.  Diablo)  and  in  magnified  ISj  diameters. 

For  the  purpose  of  checking  the  microscopical  determination  of  this 
mineral,  two  separations  and  analyses  were  made.  Though  great  care 
was  taken  in  the  separation  and  purification,  the  character  of  the  rocks 
showed  that  only  approximate  results  were  to' bo  expected.  No.  98,  Sul- 


ZOISITE.  70 

phur  Bank,  which  will  be  described  on  a  future  page,  consists  mainly  of 
glaucophane  and  zoisite;  but  fine  needles  of  the  former  penetrate  the  latter. 
The  purest  lot  of  zoisite  had  a  specific  gravity  of  3.21,  which  is  less  than 
that  of  unmixed  zoisite,  but  greater  than  that  of  glaucophane.  Its  compo- 
sition was  found  to  be  as  follows: 

Water  at  above  10'J°,  H-0 5.25 

Silica,  SiO- 39.80 

Titanic  acid,  TiO-' Trace 

Aluraiua,  AW 22.72 

Ferric  oxide,  Fe-O:> 4.  85 

Ferrous  oxide,  FeO 1.49 

Manganous  oxide,  MuO 0.  26 

Lime,  CaO 17.55 

Magnesia,  MgO  '     3.89 

Soda,  Na*O 4.09 

Potassa,  K2O 0.12 

Total 100.02 

The  atomic  ratio  H2  :  R"  :  Pcvi  :  Si  is  represented  by  2.62  :  4.54  :  6.82 
:  12.  This  clearly  does  not  correspond  to  pure  zoisite,  of  which  the  ratio 
is  1  :  4  :  9  :  12,  and  the  question  arises  whether  it  may  represent  any  other 
lime-alumina  silicate.  A  glance  at  the  minerals  of  similar  composition,  the 
density  of  which  lies  between  2.90  and  3.50,  shows  that  the  choice  is  small, 
and  in  fact,  among  known  minerals,  is  limited  to  zoisite  and  prehnite.  The 
specimen  analyzed  was  more  acid  than  zoisite,  but  more  basic  than  prehnite. 
Considering  that  the  maximum  density  of  prehnite  is  2.95  and  that  the 
known  impurity  of  the  specimen  is  acid,  the  tendency  is  all  to  the  suppo- 
sition that  the  mineral  is  zoisite.  If  one  supposes  the  admixture  to  bo 
simply  a  bisilicate  of  a  protoxide  base  and  that  this  impurity  contained 
about  one-fourth  of  the  silica,  the  above  atomic  ratio  reduces  almost  ex- 
actly to  3  :  4  :  9  :  12.  It  is  true  that  glaucophane  is  an  aluminous  amphi- 
bole  and  that  if  sesquioxides  are  subtracted  from  the  analysis  the  ratio 
4:9:12  cannot  be  exactly  preserved;  but  the  rock  also  contains  quartz 
and  the  atomic  ratio  of  zoisite  is  known  to  vary  to  some  extent.  The 
figures  discussed,  in  connection  with  the  known  impurities,  are  thus  suffi- 
cient to  show  that  the  mineral  is  not  prehnite  and  is  far  more  closely  allied 
to  zoisite  than  to  any  other  known  mineral.  There  is  an  excess  of  water 


80  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

shown  by  the  analysis,  which  seems  to  have  arisen  from  imperfect  desic- 
cation. 

A  second  separation  was  undertaken  with  No.  219,  Sulphur  Bank,  a 
rock  composed  chiefly  of  greenish  zoisite  and  actinolite,  the  former  em- 
bedded in  the  latter.  It  was  impossible  wholly  to  separate  the  two  minerals 
and  the  purest  sample  had  a  specific  gravity  of  no  less  than  3.37,  show- 
ing that  much  actinolite  remained.  The  analysis  gave  the  following 
results : 

Loss  above  100°,  H2O 1.119 

Silica,  SiO2 39.196 

Phosphoric  acid,  P2OS Trace 

Titanic  acid  (rutile),  TiO- 1.169 

Alumina,  APO3 22.760 

Ferric  oxide,  FesO3 6.487 

Ferrous  oxide,  FeO 1. 783 

Nickel  oxide,  NiO Trace 

Manganous  oxide,  MnO  0.090 

Lime,  CaO 22.023 

Magnesia,  MgO 1.  643 

Soda,  Na2O  3.382 

Potassa,  K2O 0.575 

Total 100.227 

This  analysis  gives  the  atomic  ratio  H2  :  R"  :  Rvi  :  Si  =  0.57  :  4.56  : 
7.22  :  12.  Here,  also,  if  the  admixed  silicate  has  a  protoxide  base  and  if 
it  contains  about  one-sixth  of  the  silica,  the  ratio  is  reduced  to  one  resem- 
bling that  of  zoisite,  viz,  §  :  4  :  9  :  12.  In  this  case  there  is  too  little 
water  instead  of  too  much,  but  in  performing  the  analysis  the  sample  was 
accidentally  dried  at  somewhat  above  100°. 

Although  zoisite  is  extremely  abundant  in  the  metamorphic  rocks  of 
California,  there  were  no  specimens  which  seemed  so  well  adapted  to  a 
separation  as  the  two  discussed  above.  The  manner  in  which  the  compo- 
nents of  these  rocks  are  intergrown  renders  separations  almost  impracti- 
cable. Impure  as  the  materials  analyzed  were,  however,  the  results  show 
that  the  substance  in  question  was  really  a  zoisite. 

Under  different  conditions  zoisite  possesses  a  considerable  similarity 
to  other  minerals.  Especially  when  granular,  it  might  at  first  sight  be 
confounded  with  epidote ;  but  it  is  distinguished  by  its  color,  its  mono- 


ZOISITE.  81 

chroism  or  slight  dichroism,  by  the  colors  of  interference,  and,  when  seen 
in  cross-section,  by  the  angle  of  extinction.  The  more  highly  colored 
zoisite  in  prisms  bears  a  superficial  resemblance  to  augite,  which  needs: 
only  to  be  pointed  out  to  avoid  confusion.  The  mineral  in  the  form 
of  small  prisms  and  needles  may  readily  be  confounded  with  apatite. 
The  latter,  however,  does  not  give  the  yellow  interference  tints  of  zoisite 
and  seldom  shows  .the  liglnVgreen  tint  in  natural  light  which  is  frequent 
in  zoisite.  The  index  of  refraction  of  zoisite  seems  to  be  higher  than 
that  of  apatite,  so  that  its  crystals  stand  out  in  relief  from  the  slide  sim- 
ilarly to  those  of  zircon,  though  not  to  the  same  extent.  Cross-sections 
of  zoisite  are  also  usually  square,  and  by  careful  use  of  the  micrometer 
screw  zoisite  prisms  may  usually  be  seen  to  be  fluted  or  furrowed  in  the 
direction  of  the  principal  axis,  while  apatite  prisms  display,  so  far  as  I 
know,  no  such  irregularity  of  surface.  The  distinction  between  these  min- 
erals can  be  drawn  by  one  or  more  of  these  means  in  almost  all  cases,  but 
the  discrimination  requires  watchfulness.  Microlites  of  zoisite  sometimes 
present  an  appearance  somewhat  resembling  that  of  a  rhombic  pyroxene, 
but  hypersthene  is  as  a  rule  strongly  dichroitic,  while  enstatite  is  usually 
fibrous  and  seldom  if  ever  forms  crystals.  Prehnite  is  a  mineral  which 
might  readily  be  confounded  with  zoisite,  from  which  it  is  distinguished  by 
specific  gravity  and  by  behavior  to  acids.  These  are  not  very  satisfactory 
distinctions,  because  it  is  hardly  practicable  to  test  every  slide  with  acids 
or  to  obtain  the  specific  gravity  of  the  mineral  in  every  specimen.  A  con- 
siderable number  of  such  tests  have  been  made,  however,  and  in  no  case 
did  either  test  indicate  the  presence  of  prehnite,  nor  has  prehnite  been 
detected  macroscopically. 

/oisite  in  the  recrystallizing  sandstones  not  only  forms  in  aggregates 
of  recrystallizing  minerals,  but  also  results  from  the  attack  of  quartz  grains. 
Well  developed  crystals  of  zoisite,  with  somewhat  rounded  terminal  faces, 
may  often  be  seen  growing  into  quartz  grains  from  the  outside  almost 
exactly  as  they  might  develop  iu  a  limpid  fluid.  It  must  of  course  be  sup- 
posed in  such  cases  that  there  is  a  space  between  the  ingrowing  crystal  and 
the  surrounding  quartz  which  admits  of  the  penetration  of  fluids,  though 
under  the  microscope  no  such  opening  is  visible.  If  there  is  one,  the  para- 


MON  XIII- 


82  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sitic  crystal  must  enlarge  in  diameter  as  well  as  in  length,  and  such  appears 
to  be  the  fact,  for  the  longer  crystals  are  as  a  rule  also  the  larger  ones. 

Zoisite  is  unknown  in  eruptive  rocks,  except  as  an  epigenetic  constitu- 
ent In  the  Coast  Ranges  the  relations  of  the  zoisite  to  the  disintegrating 
clastic  elements  of  the  altered  sandstones  are  such  <ns  to  forbid  any  suppo- 
sition except  that  it  is  authigenetic.  The  granites  contain  none. 

saussurits. — In  1859  Dr.  T.  SteiTy  Hunt1  showed  that  the  saussurite  of 
the  euphotide  of  Monte  Rosa  corresponded  in  chemical  composition  and 
physical  character  to  zoisite.  After  the  application  of  the  microscope  to 
the  study  of  lithology,  saussurite  was  recognized  as  (ordinarily,  at  all  events) 
a  mixture.  In  1883  Mr.  A.  Cathrein"  showed  that  many  saussurites  were 
mixtures  of  zoisite  and  feldspar.  Many  of  the  metamorphic  rocks  of  the 
Coast  Ranges  might  be  described  as  saussuritic,  but  it  appears  [inadvisable 
to  retain  distinct  names  for  mixtures  of  this  description  after  their  real  com- 
position is  established. 

.  In  the  California  rocks  this  mixture  is  not  a  product  of  decomposition 
under  ordinary  conditions,  but  of  a  process  of  recrystallization  inconsistent 
with  ordinary  decomposition.  In  Switzerland  and  elsewhere  eruptive  dia- 
basic  rocks  are  supposed  in  some  instances  to  have  been  converted  into 
saussuritic  masses,  while  in  others  decomposition  has  yielded  no  zoisite  In 
any  case  the  result  of  a  chemical  process  must  be  that  group  of  compounds 
the  formation  of  which  liberates  heat  most  rapidly.  It  is  consequently  to 
be  supposed  that  the  saussuritic  gabbros  have  been  subjected  to  influences 
different  from  those  to  which  such  gabbros  as  have  undergone  ordinary  de- 
composition have  been  exposed.  Judging  from  the  analogy  of  the  rocks 
of  the  Coast  Ranges,  it  may  be  conjectured  that  the  saussuritic  gabbros 
stand  to  ordinary  rocks  of  the  same  species  in  the  same  relation  as  the 
zoisitic  altered  rocks  of  the  Coast  Ranges  do  to  those  which  have  merely 
weathered,  or,  in  other  words,  that  the  saussuritic  rocks  are  the  result  of 
a  process  of  metamorphism  acting  upon  rocks  some  of  which  are  eruptive. 

Feldspars — The  formation  of  feldspars  is  an  almost  invariable  accom- 
paniment of  the  metasomatic  changes  of  the  rocks  of  the  quicksilver  belt, 

1  Am.  Jour.  Sci.,  2d  series,  vol.  27, 1659,  p.  336. 

a/eitschr.  fur  Kryst.  und  Mineral.,  Groth,  vol.7,  1883,  p. 234. 


FELDSPARS.  83 

and  the  only  exception  appears  to  be  in  the  case  of  the  amphibolites,  which 
seem  most  rationally  regarded  as  extreme  cases  of  the  dioritic  group.  The 
genesis  of  feldspar  in  the  metamorphic  rocks  is  certainly  one  of  the  most 
important  changes,  and  it  is  also  one  which  is  very  fully  illustrated  by  the 
collections.  The  unquestionable  authigenesis  of  minerals  of  this  group 
is  excellently  seen  in  No.  11,  Knoxville,  an  angitic  rock  intersected  by 
minute,  almost  microscopic,  veins.  Portions  of  these  veins  are  filled  with 
well  developed,  striated  feldspar  prisms  and  irregular  grains  of  plagioclase, 
seemingly  oligoclase.  In  some  portions  carbonates  are  mixed  with  these 
crystals  and  appear  to  have  crystallized  at  the  same  time  with  the  feldspar. 
These  crystals  are  more  recent  than  the  rock  in  which  they  are  embedded, 
but  they  demonstrate  that  conditions  necessary  and  sufficient  to  the  forma- 
tion of  feldspar  in  the  wet  way  have  existed  in  this  region.  The  whole  oc- 
currence is  such  as  to  exclude  the  possibility  that  these  veins  are  of  eruptive 
origin.  There  is  also  abundant  evidence  of  the  presence  of  authigenetic 
feldspar  in  the  altered  sandstones.  The  process  usually  commences  in  the 
fine  detritus  which  often  composes  the  cement  of  the  sandstones.  Here 
form  slender,  polysynthetic,  plagioclase  microlites,  of  such  shapes  and  in 
such  grouping  that  it  is  impossible  to  suppose  them  to  be  clastic  constituents. 
The  larger  grains  are  attacked  later  than  the  cement,  and  both  quartz  and 
feldspar  grains  appear  to  be  resolved  into  plagioclase,  secondary  quartz  not 
infrequently  forming  at  the  same  time.  The  corroded  grains  are  often  to 
be  seen  surrounded  by  a  fringe  of  authigenetic  plagioclase  microlites,  the 
nucleus  remaining  clear.  The  allothigenetic  feldspar  grains  are  also  often 
recrystallized  without  any  change  in  the  external  outline.  In  such  cases  an 
aggregate  results  which  is  usually  microcrystalline,  but  often  also  includes 
or  may  be  almost  entirely  composed  of  lath-like,  hemitropic  lamellae. 

There  appears  clear  evidence  of  the  process  by  which  tolerably  large 
plagioclases  may  be  formed  in  the  rocks  which  have  undergone  metaso- 
matic  recrystallization.  In  some  rocks  which  still  retain  an  indubitably 
clastic  character,  plagioclase  microlites  may  be  seen  forming  in  groups  of 
almost  identical  orientation,  but  still  separated  by  thin  layers  of  minerals 
not  belonging  to  the  feldspar  series.  Even  rough,  crystalline  outlines  may 
be  traced  surrounding  such  groups.  The  hemitropic  lamella:  in  such  cases 


84  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

usually  have  frequent  offsets,  and  the  crystallographic  orientation,  though 
nearly  the  same  for  the  whole  group,  is  not  absolutely  uniform.  It  is  ex- 
tremely difficult  to  understand  this  building  up  of  crystals  from  microlites; 
yet  perhaps  in  no  other  way  could  the  formation  of  garnets,  tourmalines, 
and  a  long  list  of  other  minerals  be  explained  in  strata  which  can'  never 
have  been  reduced  to  a  plastic  state. 

The  commonest  feldspar  species  in  the  altered  sandstones  and  the 
granular  rocks  is  oligoclase,  but  andesine  is  probably  also  common.  Many 
angles  of  extinction,  referable  to  andesine,  have  been  observed,  and  in 
one  case  a  separation  and  chemical  analysis  showed  the  presence  of  this 
feldspar.  Labradorite  is  found  in  the  gabbroitic  rocks  and  in  at  least  one 
pyroxene  rock  where  the  bisilicate  is  not  diallage.  Orthoclase  has  been 
proved  chemically  to  exist  in  one  glaucophane  rock,  and  albite  in  a  feld- 
spar-augite-hornblende  rock.  There  may  be  more  albite  than  has  been 
detected,  since  it  cannot  be  recognized  with  ease  by  optical  means  in  the 
presence  of  oligoclase. 

Runic — In  some  of  the  schists  and  amphibolites  numerous  masses  of 
a  bright-brown,  anisotropic  mineral  were  observed.  Many  of  these  masses 
are  prismatically  developed,  though  the  edges  and  corners  are  somewhat 
rounded.  They  are  monochroitic  and  extinguish  light  when  parallel  to  the 
principal  sections  of  the  nicols.  The  interference  colors  are  scarcely  dis- 
tinguishable from  those  observed  in  ordinary  light.  A  small  amount  of  this 
mineral  separated  from  an  amphibolite  proved  on  chemical  examination  to 
be  titanic  acid.  The  absence  of  dichroism  and  of  brilliant  colors  of  inter- 
ference shows  that  it  is  not  brookite.  The  prismatic  development  excludes 
anatase,1  while  its  characteristics  correspond  exactly  to  those  of  rutile.  Some 
of  the  masses  of  rutile  are  partially  decomposed  to  a  light-colored,  clouded 
substance  similar  to  leucoxene. 

iimenite. — Titanic  iron  is  very  abundant  in  some  of  the  groups  of  gran- 
ular, metamorphic  rocks,  and  the  associations  are  such  as  to  lead  to  the  sup- 
position that  it  has  been  formed  at  the  same  time  with  the  bisilicates.  The 
characteristic  triangular  grating  of  the  iimenite  is  much  more  common  in 
these  rocks  than  it  usually  is  in  eruptive  masses.  The  ilmeiiite'is  frequently 

1  See  a  report  of  an  investigation  by  Thiiracb:  Neues  Jahrbucb  liir  Miuvral.,  vol.  2,  18ri5,  p.  '.VM. 


COMPONENT  MINERALS.  85 

accompanied  by  clouds  of  leucoxene.     The  appearance  of  this  material  is 
entirely  accordant  with  the  supposition  that  it  is  granular  titanite. 

Titamte. —  Besides  the  clastic  grains  of  this  mineral  in  the  sandstones,  it 
appears  in  the  glaucophane  schists  in  characteristic  rhomboid  forms,  the 
corners  being  wholly  unabraded.  In  the  same  rocks  it  appears  as  more  or 
less  regular  grains,  embedded  in  zoisite  and  in  entirely  undecomposed  glau- 
cophane. It  is  thus  to  be  considered  as  an  authigenetic  component  of  these 
rocks,  apparently  replacing  the  ilmenite  of  the  granular  group.  The  colors 
in  ordinary  and  in  polarized  light  and  the  other  optical  properties,  as  well  as 
the  form,  are  entire!}'  characteristic  and  require  no  comment. 

Apatite. —  This  mineral  having  been  detected  by  optical  and  chemical 
means  as  an  authigenetic  constituent  in  one  slide,  a  special  examination  of 
the  collection  was  made  for  fear  that  it  might  have  been  mistaken  for  zoisite. 
It  was  found  in  abundance  in  some  of  the  pyroxene  granular  rocks  and  in 
two  glaucophane  schists.  Minute  prisms  of  this  mineral  appear  also  to  be 
present  in  a  few  of  the  altered  sandstones.  Apatite  is  tolerably  frequent  as 
an  inclusion  in  clastic  grains. 

chiorites. —  Chlorites  are  abundant  both  in  the  sandstones  and  in  the 
recrystallized  rocks  which  are  undergoing  weathering.  As  usual,  it  is  dif- 
ficult to  determine  the  particular  species  of  chlorite ;  indeed,  the  specific 
distinctions  between  these  minerals  are  far  from  satisfactory.  All  of  the 
chlorite  met  with  possesses  the  usual  grass-green  tint  and  is  strongly  di- 
chroitic.  It  is  usually  fibrous,  but  in  a  few  cases  shows  irregular  scales. 
The  fibers  always  extinguish  light  when  sensibly  parallel  to  the  principal 
section  of  the  polarizing  apparatus,  while  some  of  the  scales  appear  to 
remain  absolutely  dark  between  crossed  nicols.  The  interference  colors  of 
the  fibrous  aggregates  vary  greatly.  When  the  mass  is  composed  of  felted 
libers  of  minute  size  the  colors  of  polarization  are  very  feeble.  In  other 
cases  dark-blue  tints  appear,  and  in  some  instances,  which  appear  to  be 
distinguished  by  unusually  large  quantities  of  parallel  individuals,  yellow 
interference  colors  make  their  appearance.  By  treatment  through  a  per- 
forated cover  with  moderately  strong,  warm  chlorhydric  acid,  it  was  found 
that  the  ordinary  fibrous  chlorite  of  these  rocks  is  not  attacked.  Portions 
of  the  same  specimens,  however  (e.  g ,  No.  26,  Sulphur  Bank),  treated  with 


86  QUICKSILVEli  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

boiling,  concentrated  chlorhydric  acid,  yielded  a  .solution  containing  both 
alumina  and  magnesia.  Clinochlor  is  thus  absent.  None  of  the  specimens 
affords  an  opportunity  of  isolating  the  chlorite  in  sufficient  quantities  for 
quantitative  analysis.  Pennine  is  stated  to  occur  characteristically  in  hexag- 
onal scales,  which  are  readily  attacked  by  chlorhydric  acid.1  It  is  possible  that 
the  rather  rare  irregular  foils  mentioned  above  belong  to  this  species;  but  the 
fibrous  variety  is  certainly  not  easily  attacked  by  the  acid.  Of  the  ordinary 
chlorites  there  remains  only  the  ripidolite  of  Rose,  which  is  Werner's  chlo- 
rite and  Dana's  prochlorite.  It  is  to  be  hoped  that  the  researches  of  Pro- 
fessor Tschermak  will  make  future  determinations  more  satisfactory  than  this. 
Epidote. — Epidote  is  not  very  abundant  in  the  metamorphic  rocks.  In 
a  single  specimen,  however  (No.  119,  Knoxville),  it  is  developed  in  large 
crystalline  grains  with  two  cleavages,  and  in  this  case  greatly  resembles 
augite.  The  optical  reference  of  this  specimen  was  confirmed  by  a  silica 
determination,  which  was  38.98  per  cent.  The  usual  occurrence  of  this 
mineral  is  in  crystalline  aggregates  in  association  with  chlorite,  to  which  it 
often  stands  in  relations  strongly  suggesting  epigenesis  from  chlorite.  No 
cases  so  fine  as  those  described  and  figured  in  my  memoir  on  the  Comstock 
lode  were  met  with.  Professor  Rosenbusch2  doubts  my  explanation  of 
those  occurrences,  believing  that  they  are  not  of  such  a  nature  as  to  pre- 
clude the  simultaneous  formation  of  the  two  minerals.  It  is  difficult  to  prove 
absolutely  that  they  were  not  formed  at  the  same  time,  because  of  the  lack 
of  persistent  structure  in  the  chlorite;  yet,  from  the  inspection  of  almost 
numberless  cases,  it  certainly  appears  that  epidote  needles  pierce  aggre- 
gates of  chlorite  fibers  freely,  while  the  arrangement  of  these  fibers  does 
not  bear  any  visible  relation  to  the  epidote  crystals  such  as  is  familiar  in 
cases  of  simultaneous  formation.  When  I  first  expressed  my  opinion  on 
this  subject  I  was  unaware  that  other  lithologists  had  reached  the  same 
conclusion.  Both  Dr.  H.  Francke  and  Prof.  A.  Renard  anticipated  me  in 
what  I  still  regard  as  the  most  probable  explanation.3 

1  FouqiKi  and  Michel-LeVy  :  Mill,  micrographique,  p.  438. 

"Neues  Jahrbnch  fiir  Mineral.,  vol.  %2,  1884,  p.  187. 

3  Dr.  Francke's  paper,  Studien  iiber  CordillereHgesteine,  Inaug.  Uiss.,  Leipzig,  187;"),  I  have  not  seen. 
The  following  is  an  extract  from  Mr.  Renard's  paper  on  the  diabase  of  C'balles  (Bull.  Acad.  roy.  Bel- 
gique,  vol.  4(i,  No.  8,  1H78,  p.  239-) :  "Francke  admits  that  the  epidote  is  formed  by  the  decomposi- 
tion of  the  viridite  included  in  the  feldspars,  the  viridite  itself  arising  from  the  decomposition  of  horn- 


ALTERED  SANDSTONES.  87 

Gamet. — In  the  glaucophane  schists  garnets  are  not  infrequent,  though 
nowhere  very  abundant,  in  crystals  measuring  from  0.3mm  to  2mm.  The 
garnet  is  of  a  pale  reddish-brown  tint,  perfectly  isotropic,  and  includes  zo- 
isite,  titanite,  and  glaucophane.  It  decomposes  to  a  coarsely  foliated  chlo- 
rite. Nothing  answering  to  the  kelyphite  of  Mr.  A.  Schrauf1  has  been 
observed,  and  it  can  only  be  supposed  that  the  decomposition  has  been 
effected  by  the  action  of  magnesian  waters.  Serpentine  is  also  associated 
with  the  decomposing  garnets,  but  riot  under  conditions  sufficiently  pro- 
nounced in  the  material  at  hand  to  justify  any  positive  assertions  as  to  the 
relations  of  the  two  minerals. 

other  minerals. — Zircon  is  common  as  an  inclusion  in  clastic  grains  and  is 
also  probably  present  in  some  of  the  glaucophane  schists.  A  careful  watch 
has  been  kept  for  other  minerals,  such  as  andalusite,  dipyre,  prehnite,  allan- 
ite,  and  zeolites.  The  last  occur  macroscopically  in  the  New  Almaden 
mine,  but  have  not  been  observed  in  the  slides. 


AI.TF.RKI>   SANDSTONES. 


In  various  specimens  of  altered  sandstone  one  or  other  process  of 
transformation  may  be  lacking  or  insensible,  but  in  a  number  of  cases 
a  single  slide  furnishes  an  almost  complete  epitome  of  the  entire  series. 
I  do  not  think  it  possible  to  convey  to  the  reader  a  better  idea  of  the 
metamorphism  of  the  sandstones  than  by  describing  a  few  typical  in- 
stances. 

Examples. — A  good  example  of  an  altered  sandstone  is  afforded  by  a 
rock  from  near  Knoxville.2  Macroscopically  it  is  a  dark-green,  fine-grained 
sandstone,  evidently  somewhat  altered.  Seen  under  the  microscope  with  a 
low  power  it  appears  to  be  a  typical  sandstone,  with  only  insignificant 
changes.  With  a  No.  4  Hartnack  it  is  seen  to  contain  numerous  unaltered 

blende.  The  statements  applicable  to  the  viridite  of  the  hornblende  from  Franoke's  point  of  view 
are  true  also  of  the  chloritic  material  derived  from  angite  and  which,  as  we  have  seen,  so  often  fills 
feldspathic  sections,  for  these  two  substances,  so  imperfectly  determined  from  a  chemical  point  of  view, 
present  fundamental  analogies  in  composition.  We  have  been  led  to  regard  the  epidote  inclosed  in  feld- 
sparsections  not  as  psendomorphic  after  feldspar,  but  as  a  result  of  the  transformation  of  chloritic 
matter.  There  are,  furthermore,  numerous  instances  of  this  transformation." 

'Zeitschr.  fiir  Krys.  uud  Mineral.,  Oroth,  vol.  (>,  p.  321. 

8  No.  8,  Coast  Eauge  collection,  bed  of  Jericho  Creek. 


88 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


grains  of  granitic  quartz  and  feldspars,  but  it  also  becomes  apparent  that 
a  great  proportion  of  the  allothigenetic  minerals  have  been  converted 
into  aggregates  of  new  minerals.  Especially  important  is  the  presence  in 
this  slide  of  unquestionably  authigenetic  augite  and  hornblende.  Augite 
occurs  in  several  places  under  circumstances  which  place  its  authigenetic 
character  beyond  doubt.  Of  these  the  best  is  illustrated  in  the  accompa- 
nying Fig.  2.  It  is  a  slightly  greenish  prism  with  terminal  faces  forming 
angles  on  the  right  and  left  sides,  respectively,  of  l'2b°  and  128°,  and  an 
angle  of  extinction  of  about  30°.  It  occurs  in  a  crystalline  aggregate  fill- 
ing the  position  of  a  clastic  grain  of  which  the  outlines  are  traceable.  The 
portion  not  occupied  by  the  augite  is  composed  of  macrocrystalline  feld- 
spar and  quartz.  There  are  also  films  of  serpentine  among  the  grains. 
The  upper  right-hand  corner  of  the  augite  is  changed  to  uralite. 


FIG.  2.  Authigenetic  angitc  in  altoml  sandstone,  No.  8,  Coast  Ranges.    A,  augite;  w,  nralite;  /,  mioiocrystallino  feld- 
spar; 7,  quartz  grain  ;  »,  serpentine.    Magnified  11?  diameters. 

Authigenetic  hornblende  of  light-brown  color  is  also  present,  and  the 
best  example  appears  in  the  following  Fig.  3.  It  is  surrounded  on  two 
sicles  by  microcrystalline,  authigenetic  feldspar  and  lies  against  a  clastic 
orthoclase  grain.  As  appears  from  the  cut,  a  large  part  of  the  outline  is  as 
sharp  as  possible.  The  unabraded  corners,  the  color  and  character  of  the 
mineral,  and  the  association  all  forbid  its  being  regarded  as  allothigenetic. 
On  the  left  side  are  a  number  of  hornblende  microlites  in  parallel  position, 
apparently  representing  the  incomplete  portion  of  the  crystal. 


ALTERED  SANDSTONES. 


89 


Various  other  phenomena  can  be  studied  in  this  slide:  Zoisite,  in  prisms 
and  granular  masses,  is  developing  in  some  of  the  clastic  grains;  triclinic 
feldspar,  in  grains  and  in  polysynthetic  microlites,  is  forming  in  others; 
and  the  resolution  of  quartz  as  well  as  oT  feldspar  can  be  observed.  White 
mica  is  forming  authigeneticallv,  and  perhaps  also  apatite.  Decomposition 
has  also  set  in  and  the  slide  contains  some  serpentine.  These  phenomena 
are  better  observed,  however,  in  other  cases. 


Fir,.  H.  Authigenetic  hornblende  in  altered  sandstone,  No.  8,  Coast  Ranges,  a,  clastic  quartz;  b,  clastic  feldspar;  c, 
authi^euetH'.  hornblende;  <l,  OUtfalgenetic  feldspar  aggregate  ;  e,  clear  isotvopio  mass;  s,  serpentine.  Magnified  170 
diameters. 

Xo.  86,  New  Idria,  is  a  coarse,  bedded,  dark  greenish-gray  sandstone, 
evidently  altered,  but  manifestly  a  sandstone.  Under  the  microscope  the 
clastic  character  is  clearly  visible,  the  original  limits  of  the  grains  being 
defined  by  irregular  streaks  of  brown  or  greenish  color.  Some  of  these 
streaks  represent  decomposed  mica  foils.  In  the  clear  masses  separated  by 
the  colored  streaks  are  embedded  angular  and  rounded  grains,  many  of 
which  are  quartz  carrying  abundant  fluid  inclusions,  while  others  are  feld- 
spar. Surrounding  these  nuclei  are  aggregates,  chiefly  feldspathic,  and  these 
aggregates  are  so  related  to  the  nuclei  that  it  is  impossible  to  doubt  that  they 
are  composed  of  authigenetic  minerals  formed  at  the  expense  of  clastic 
grains,  only  the  central  portions  of  which  remain.  Many  of  the  residual 
grains  are  almost  entirely  surrounded  by  elongated  microlites  in  positions 
nearly  normal  to  the  surface  of  the  nucleus.  The  ends  of  the  microlites 
do  not  merely  abut  against  the  nucleus,  but  penetrate  it  for  a  sensible  dis- 


90  (.U'lCKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

tance,  so  that  the  edge  of  the  grain  seen  in  section  is  full  of  indentations, 
each  the  bed  of  a  microlite.  This  relation  is  more  clearly  seen  by  revolv- 
ing the  analyzer.  In  positions  where  the  colors  of  the  host  are  strong  while 
those  of  the  parasites  are  weak,  the  original  mineral  is  seen  to  extend  out 
among  the  microlites,  while,  when  the  relations  of  the  colors  are  reversed, 
the  nucleus  appears  limited  nearly  to  the  inner  ends  of  the  microlites.  As 
the  polarizer  revolves,  the  visible  limits  of  the  parent  mineral  dilate  and  con- 
tract in  a  very  striking  manner. 

In  many  cases  the  nuclei  are  quartz  and  the  microlites  are  poly- 
synthetic  twins,  which  in  favorable  cases  give  the  angles  of  extinction  of 
oligoclase.  In  other  cases  the  nuclei  are  feldspar,  sometimes  orthoclase  and 
again  plagioclase ;  the  parasitic  microlites,  however,  again  appear  to  be 
chiefly  oligoclase.  That  oligoclase  should  result  under  the  same  conditions 
from  the  attack  of  quartz  and  of  feldspar  is  in  the  highest  degree  remark- 
able ;  but  the  observations  made  on  this  slide  and  confirmed  by  comparison 
with  other  thin  sections  admit  of  no  other  simple  explanation.  The  process 
of  alteration  does  not  go  on  only  at  the  surface  of  the  quartz  grains.  In 
the  granites  quartz  grains  are  frequently  composite,  the  separate  crystalline 
individuals  sometimes  exhibiting  a  barely  perceptible  difference  in  crys- 
tallographic  orientation.  The  lines  dividing  the  individuals  must  also  be 
lines  of  weakness,  and  when  the  fractures  which  take  place  in  the  disinte- 
gration of  the  parent  rock  do  not  follow  these  lines  they  may  often  be  seen 
to  have  afforded  opportunities  for  the  attack  of  the  solutions  and  to  be 
marked  by  narrow  bands  of  microlites  nearly  perpendicular  to  the  line  of 
division. 

It  is  not  always  that  the  microlites  resulting  from  the  attack  of  quartz 
and  feldspar  in  this  rock  are  lath-like.  In  many  cases  they  take  the  form 
of  irregular  grains  indenting  one  another  and  assuming  the  granophyr-like 
structure  mentioned  in  the  slide  from  Jericho  Creek.  These  grains  are  not 
polysynthetic,  but  evidently  feldspathic,  and  are  so  associated  with  the 
elongated  microlites  as  to  make  it  probable  that  they  are  of  the  same  or  a 
closely  allied  species. 

This  slide  also  contains  small  quantities  of  zoisite  and  some  undeformed 
foils  of  white  mica  embedded  in  aggregates  which  have  replaced  clastic 


ALTERED  SANDSTONES.  91 

grains.     Both  of  these  minerals  are  authigenetic.    There  are  also  decompo- 
sition products,  including  a  little  serpentine. 

No.  134,  Sulphur  Bank,  is  manifestly  a  much  altered,  arenaceous  rock, 
of  a  strong  green  tinge,  intersected  by  minute  veins  of  a  feldspar-like  min- 
eral. Under  the  microscope  the  clastic  character  is  perfectly  distinct,  the 
clear  or  somewhat  milky  grains  being  divided  by  a  net-work  of  thoroughly 
characteristic  conformation.  The  net  is  composed  of  green  and  brownish- 
green  matter.  The  original  clastic  minerals  have  entirely  disappeared. 
The  thin  section  shows  half  a  dozen  minute  veins,  more  or  less  continuous, 
and  these  are  filled  with  feldspar,  which  is  for  the  most  part  granular, 
but  occasionally  shows  irregular,  hernitropic  lamelhe.  On  the  course  of  one 
of  the  veins,  at  a  point  at  which  the  vein  pinches,  is  a  very  remarkable 
feldspar  aggregate  of  lath-like  microlites  extending  over  an  area  several 
times  as  wide  as  the  adjacent  vein.  This  aggregate  has  replaced,  wholly 
or  in  part,  several  clastic  grains  the  shape  of  which  is  faintly  trace- 
able by  brownish  streaks.  Three-fourths  of  the  periphery  of  the  aggregate 
is  nevertheless  bounded  by  straight  lines.  The  aggregate  is  composed  of 
polysynthetic,  lath-shaped  microlites  almost  exactly  parallel  to  one  another 
and  giving  low  angles  of  extinction  on  each  side  of  the  twinning  plane. 
The  position  of  these  microlites  corresponds  to  the  straight  outlines  and 
the  entire  aggregate  appears  to  represent  a  porphyritic,  authigenetic  feld- 
spar cut  nearly  perpendicular  to  the  brachypinacoid  and  showing  two 
distinct  terminal  outlines  at  one  end.  The  chief  distinction  between  this 
and  porphyritic  feldspar  in  eruptive  rocks  is  the  frequent  interruption  of 
the  hemitropic  lamella?.  The  traces  of  the  original  outlines  of  the  clastic 
fragments  still  visible  in  the  feldspar  forbid  the  supposition  that  it  is  an 
allothigenetic  mineral;  neither  is  it  possible  that  such  a  crystal  should  have 
been  transported  and  redeposited  without  abrasion  of  its  corners.  The 
slide  .shows  snveral  other  feldspars  oT  similar  character,  but  less  perfectly 
developed.  The  greenish-brown  net-work  between  the  altered  grains  in 
this  slide  is  chiefly  composed  of  a  non-dichroitic,  fibrous  mineral  show- 
ing dull-yellow  interference  colors  and  thus  corresponding  to  serpentine. 
There  are  no  patches  of  it  large  enough  to  show  the  characteristic  grate 
structure. 


92  QUICKSILVEli  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

No.  212«,  Sulphur  Bank,  is  a  dull-green  sandstone  intersected  by 
quartz  veins.  Under  the  microscope  it  is  seen  to  be  a  partially  decomposed 
sandstone,  containing  numerous  fragments  of  quart/,  orthoclase,  and  pla- 
gioclase,  the  interstices  being  in  part  filled  with  serpentine.  The  slide  is 
chiefly  remarkable  for  the  presence  of  zoisite  in  considerable  quantities, 
growing  into  the  quart/  grains.  The  zoisite  shows  the  characteristic  extinc- 
tions, interference  colors,  refraction,  and  cross-section. 

No.  15,  Sulphur  Bank,  an  ordinary  gray,  indurated  sandstone,  shows 
phenomena  similar  to  those  described  in  No.  86,  New  Idria.  It  also  con- 
tains a  great  deal  of  zoisite,  both  in  the  granular  and  the  prismatic  form. 
The  zoisite  in  this  slide  was  tested  with  nitric  acid  to  make  sure  that  apatite 
had  not  been  mistaken  for  it. 

An  especially  significant  rock  is  No.  13,  New  Almaden,  which  is 
both  macroscopically  and  microscopically  unquestionably  an  altered  sand- 
stone. In  the  slide,  however,  it  is  seen  that  the  progress  of  the  metaso- 
matic  recrystallization  has  been  somewhat  irregular  and  that  there  are 
fields  in  the  slide  which  could  not  be  distinguished  from  an  ordinary  eruptive 
diabase.  As  the  slide  is  moved,  however,  the  structure  and  mineral  compo- 
sition change  gradually  and  by  insensible  degrees  until  the  eruptive  habitus 
is  lost  and  the  clastic  character  is  clearly  revealed.  There  is  no  suggestion 
of  included  fragments  or  dikes  of  eruptive  rock  in  the  specimen  or  slide. 

No.  13,  Sulphur  Bank,  a  slightly  altered  sandstone  from  the  meta- 
morphic  series,  was  selected  for  chemical  analysis.  Under  the  microscope 
the  rock  appears  to  be  arcose,  the  grains  being  quartz  similar  to  those  of  the 
granites,  plagioclase,  and  unstriated  feldspars,  with  the  optical  properties  of 
orthoclase.  The  grains  are  cemented  by  newly  formed  aggregates  which 
seem  to  consist  in  great  part  of  triclinio  feldspar.  From  inspection  one 
would  expect  to  find  in  this  rock  about  equal  quantities  of  soda  and  pot- 
ash. The  following  analysis,  however,  shows  a  very  different  and  unex- 
pected relation  : 

Loss  at  100°,  H-O 0.276 

Loss  above  100°,  H-O 2.113 

Silica,  SiO* 68.500- 

Phosphoric  acid,  I»O» 0.163 

Titanic  acid,  TiO2 0.600 


GEANULAll  METAMOKPHICS.  93 

Alumina,  AW 12.816 

Ferric  oxide,  Fe-'O3 1.293 

Ferrous  oxide,  FeO 3.373 

Munganons  oxide,  MnO 0. 023 

Lime,  CaO ...~..r 1.823 

Magnesia,  MgO 2.206 

Soda,  Na-O 6.  0:!3 

Potassa,  K-O 1.2.VJ 

100. 478 

The  atomic  ratio  represented  by  this  analysis  is  IP  :  R"  :  ttvl  :  Si  — 
0.26G  :  0.490  :  0.801  :  4.567.  How  the  soda  can  be  so  greatly  in  excess 
of  the  potash  in  such  a  rock  I  cannot  explain.  The  cementing  ft'ldspathic 
mass  may  be  very  rich  in  soda  and  possibly  some  of  the  unstriated  feld- 
spars are  triclinic.  It  is  also  possible  that  the  orthoclase  is  abnormally  sodic. 

These  examples  show  that  nearly  all  of  the  most  important  metaso- 
matic  processes  can  be  traced  in  rocks  the  clastic  character  of  which  could 
be  questioned  by  no  one  for  a  single  moment.  It  is  only  necessary  to  sup- 
pose the  same  processes  carried  further  to  obtain  a  product  in  which  the 
clastic  character  is  obscured  or  obliterated,  and  the  altered  sandstones, 
under  the  microscope  no  less  than  in  the  field,  thus  form  transitions  from 
the  clastic  series  to  the  holocrystalline  rocks.  The  enlargement  of  clastic 
grains  by  crystallization  from  infiltrating  solutions,  which  has  been  shown 
by  several  geologists *  to  be  not  infrequent  in  some  regions,  and  of  which 
I  too  have  studied  fine  examples,  has  not  been  observed  in  the  rocks  here 
described.  The  general  nature  of  the  changes  here  consists  in  the  attack  of 
clastic  constituents,  not  in  the  addition  of  mineral  matter  of  the  same  kind. 

GRANULAR   METAMORPIIICS. 

Nomenclature — There  are  in  many  parts  of  the  world  metamorphic  rocks 
very  closely  resembling  diabase  and  diorite  in  mineral  composition- 
These  rocks  have  sometimes  been  called,  by  myself  as  well  as  by  others, 
metamorphic  diabases  and  metamorphic  diorites;  but  there  are  serious  ob- 
jections to  these  terms.  A  diabase  would  be  defined  by  most  geologists  as 
a  Pre-Tertiary  eruptive  rock,  mainly  composed  of  plagioclase  and  pyrox- 
ene. This  is  also  the  historical  meaning  of  the  term.  To  those  who  have 

1  .See  Hunt,  Origin  of  Crystalline  Rocks,  $  116. 


91  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPF. 

this  definition  in  mind  the  name  metamorphic  diabase  would  not  convey 
the  idea  of  a  metamorphic  rock  resembling  a  diabase,  but  of  an  eruptive 
rock  changed  by  metamorphic  processes.  Even  if  diabase  were  usually 
understood  to  signify  a  rock  of  a  certain  age  and  a  particular  mineral  com- 
position, irrespective  of  origin,  the  term  metamorphic  diabase  would  be 
inconvenient  on  account  of  its  length.  If  it  were  in  frequent  use,  it  would 
often  be  contracted  to  diabase,  and  this  term  would  lead  to  misunderstand- 
ings. It  seems  eminently  desirable  to  retain  for  diabase  and  diorite  the 
meanings  which  they  have  long  conveyed  to  geological  readers  and  to  limit 
their  application  to  eruptive  masses.  Metamorphic  rocks  which  resemble 
them  in  mineral  composition  may  then  fitly  be  called pseudodiabase  smApsett- 
dodioritc,  and  these  terms  will  be  employed  in  the  remainder  of  this  report. 

Groups  of  granular  metamorphic  rocks. Tll6     granular     Crystalline     TOcks     of     tllC 

Coast  Ranges  are  divisible  according  to  their  mineralogical  composition 
into  several  more  or  less  well-defined  groups,  between  which,  however, 
there  are  transitions,  as  there  also  are  between  the  granular  and  the 
schistose  rocks.  The  chief  divisions  are  pseudodiabase  and  pseudodiorite. 
The  pseudodiabase  is  sometimes  met  in  gabbroitic  modifications  and  in 
a  few  cases  contains  so  much  zoisite  that  it  might  without  impropriety  be 
denominated  a  zoisite  pseudodiabase;  for,  since  it  has  been  shown  that 
saussurite  is  either  mere  zoisite  or  a  mixture  of  zoisite  and  plagioclase, 
there  appears  to  be  no  reason  for  retaining  that  name.  The  pseudodiorite 
passes  by  gradations  into  a  mass  so  highly  hornblendic  as  to  deserve  the 
name  of  amphibolite.  There  are  also  a  few  rocks  in  which  no  augite  or 
amphibole  appears,  and  which  are  thus  composed  of  feldspar,  quartz,  zois- 
ite, etc.  These  appear  to  represent  pseudodiabase  or  pseudodiorite  in  ex- 
treme forms,  since  they  are  locally  associated  with  these  rocks,  as  are  also 
the  slightly  altered  sandstones. 

The  schistose  rocks  are  all  characterized  by  tae  presence  of  glauco- 
phane  and  zoisite.     They  are  usually  micaceous,  but  sometimes  not. 

PSEUDODIABASE. 

Pseudodiabase  is  much  the  commonest  of  the  crystalline  metamorphic 
"ocks  of  the  Coast  Ranges.     When  sufficiently  coarse  in  texture  it  is  readily 


i 


PSEUDODIABASE. 

seen  with  the  naked  eye  to  be  a  crystalline  mass,  though  it  could  rarely  be 
mistaken  for  an  eruptive  rock.  It  then  shows  dark-green  bisilicates  and 
sometimes,  also,  feldspar  grains.  The  absence  of  visible  feldspar  grains 
corresponds  to  a  microcrystalline  groundrnmss.  Very  frequently  the  rock 
is  fine  grained,  and  then  it  sometimes  retains  the  appearance  of  an  altered 
sandstone  so  perfectly  that  it  is  impossible  to  discriminate  between  this 
and  pseudodiabase  without  the  aid  of  the  microscope. 

Under  the  microscope  it  is  found  that  at  least  a  portion  of  the  augite 
exists  in  comparatively  large  grains  or  crystals,  while  the  feldspar  may 
be  granular  or  microcrystalline.  In  other  words,  as  sometimes  happens 
among  eruptive  rocks,  both  granular  and  somewhat  porphyritic  forms  of 
pseudodiabase  are  common  and  are  intimately  associated.  Under  the  cir- 
cumstances a  difference  in  chemical  composition  appears  to  be  a  necessary 
inference  from  this  difference  in  structure. 

Orthoclase  has  not  been  detected  in  the  pseudodiabase.  Plagioclase 
usually  forms  the  greater  portion  of  the  rock.  In  those  rocks  in  which  the 
feldspathic  mass  is  microcrystalline  it  forms  a  mass  of  minute  interlocking 
grains,  sometimes  resembling  granophyre.  These  minute  grains  seldom  ex- 
hibit polysynthetic  structure  and  cannot  be  referred  to  their  proper  species 
by  optical  methods.  A  separation  and  partial  analysis  of  a  typical  occur- 
rence of  this  material,  No.  105,  Knoxville,  showed  that  it  approaches  an- 
desine  in  specific  gravity  and  composition.  In  the  rocks  in  which  the 
plagioclase  grains  reach  O.lmm  and  upwards  in  length,  twin  structure  is 
usual  and  lath-shaped  individuals  are  common.  The  heraitropic  lamella1 
are  often  irregular,  showing  breaks  and  offsets.  The  extinctions  refer  them 
to  oligoclase  or  andesine.  Porphyritic  feldspars  are  uncommon,  but  not 
wholly  wanting.  Altogether  the  most  ordinary  inclusion  in  the  feldspar 
consists  of  grains  and  prisms  of  zoisite.  These  are  not  products  of  the 
decomposition  of  the  feldspar,  but  .of  contemporaneous  development,  both 
minerals  being  often  perfectly  fresh.  When  the  pseudodiabase  has  not 
been  subjected  to  serpentinization  the  feldspars  are  often  affected  by  a 
decomposition  process  resulting  in  the  formation  of  irregular  grains  of  a 
colorless  substance  which  gives  orange  tints  between  crossed  nicols.  Its 


96  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

nature  is  uncertain.  Distinctly  developed  nacrite  has  been  detected  in  only 
one  of  the  rocks. 

Much  of  the  quartz  in  the  pseudodiabases  is  secondary,  but  in  a  few 
cases  quartz  grains  appear  to  have  formed  contemporaneously  with  the 
feldspars.  They  carry  a  few  fluid  inclusions. 

No  rhombic  pyroxene  has  been  detected.  In  the  extremely  rare  cases 
in  which  crystals  of  pyroxene  extinguish  light  when  parallel  to  the  princi- 
pal nicol  sections,  there  appears  no  difference  between  their  dichroism  or 
other  properties  and  those  of  the  other  pyroxenes  in  the  same  slide.  The 
proportion  of  cases  in  which  the  extinction  of  the  pyroxene  crystals  sensi- 
bly coincides  with  the  principal  axis  is  very  small  and  not  greater  than 
might  be  expected  in  the  case  of  a  monoclinic  mineral.  Both  augite  and 
diallage  occur,  but  no  sharp  line  can  be  drawn  between  them.  In  nearly 
all  cases  the  clinopinacoidal  cleavage  of  the  larger  crystals  seems  well 
developed.  Pyroxene  evidently  develops  early  and  vigorously  in  the  rocks 
undergoing  recrystallization  and  tends  to  the  formation  of  porphyritic 
crystals.  Well -developed  crystals  ai-e  not  very  common. 

Amphibole  occurs  as  brownish-green  crystals,  formed  contemporane- 
ously with  the  augite  and  more  abundantly  as  unmistakable  uralite.  A 
few  of  the  pseudodiabases  also  carry  glaucophane. 

Examples. — No.  21,  Coast  Ranges,  from  near  Mt.  St.  Helena,  is  a  gray, 
rather  fine-grained  rock,  which,  on  close  inspection,  appears  crystalline. 
Under  the  microscope  it  is  seen  to  contain  much  augite  and  hornblende, 
together  with  feldspar,  both  polysynthetic  and  monosynthetic,  and  an  unu- 
sually large  quantity  of  zoisite.  It  is  also  unusually  free  from  decomposi- 
tion products.  This  rock  represents  both  the  pseudodiabase  and  pseudo- 
diorite,  between  which  there  is  no  sharp  division. 

The  hornblende  is  in  part  of  a  clear,  light,  but,  not  vivid,  brown  color, 
with  very  moderate  dichroism.  This  variety  occurs  in  well  developed  crys- 
tals, giving  normal  extinctions  and  cross-sections.  Curiously  associated 
with  it  is  a  light- green  variety.  Many  of  the  crystals  are  in  part  brown 
and  in  part  green,  the  division  being  a  sharp,  straight  line.  The  different 
portions  of  such  composite  crystals  extinguish  simultaneously,  but  usually 
give  very  different  interference  colors.  The  cleavages  are  continuous  from 


PSEUDODIABASE.  97 

one  portion  to  the  other,  nor  does  the  green  mineral  exhibit  greater  fibra- 
tion  or  any  other  structural  peculiarity.  In  some  cases  the  line  of  demar- 
kation  is  curvilinear,  but  nowhere  does  the  green  color  follow  cleavages  or 
cracks  or  penetrate  the  brown  by  sharplndentation,  as  products  of  altera- 
tion usually  do.  There  seems  nothing  to  indicate  that  the  two  varieties  have 
notformed  simultaneously,  and  even  on  this  supposition  the  sharpness  of  de- 
markation  and  the  character  of  the  limits  are  difficult  to  understand.  There 
is  a  little  ordinary  chlorite  in  the  slide,  produced  by  decomposition  of  horn- 
blende. 

The  augite  possesses  no  peculiarity  excepting  its  relations  to  the  horn- 
blende. There  is  some  ordinary  uralite,  but  there  are  also  augite  masses 
partly  surrounded  by  brown  hornblende  in  such  a  way  as  to  suggest  a  brown 
uralite.  The  relation  of  the  brown  hornblende  to  the  augite,  however,  io 
similar  to  that  which  the  green  hornblende  bears  to  the  brown,  and  I  cannot 
satisfy  myself  that  it  is  really  epigenetic. 

The  feldspar  is  for  the  most  part  clear  and  fresh,  and  a  large  portion 
of  it  shows  polysynthetic  structure.  The  extinctions  observed  indicate  the 
presence  of  oligoclase.  To  test  the  character  of  the  feldspar,  a  separation 
was  made  by  the  Thoulet  method.  At  a  density  of  2.85  a  large  precipi- 
tate of  bisilicates  and  zoisite  fell,  carrying  a  portion  of  the  feldspars  with  it. 
On  reducing  the  specific  gravity  of  the  solution  gradually,  5  per  cent,  fell 
at  2. Go,  which  appeared  under  the  microscope  to  be  pure  feldspar.  Between 
2.65  and  2.58  there  was  no  precipitate.  From  2.58  to  2.56,  7  per  cent,  of 
pure  feldspar  fell.  This  was  found  to  contain  11  per  cent,  of  soda,  and 
the  rock,  therefore,  contains  both  oligoclase  and  albite.  The  zoisite  occurs 
in  part  in  prisms  with  characteristic  properties,  but  mainly  as  granular 
masses,  which  are  nearly  colorless  and  monochroitic,  but  otherwise  not 
unlike  epidote  in  appearance.  Exactly  such  zoisite  was  isolated  from  a 
Mt.  Diablo  specimen  and  chemically  tested.  The  greater  part  of  the  zoisito 
is  embedded  in  the  clear  feldspar,  but  it  also  nils  interstices  between  feld- 
spars, so  that  the  formation  of  the  two  minerals  must  have  gone  on  simul- 
taneously. 

MON,  XXII 7 


98  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Ilmenite  in  part  converted  to  leucoxene  is  abundant  in  this  as  in  most 
of  the  pseudodiabases  and  pseudodiorites.  A  complete  analysis  of  this 
rock  gave  the  following  result: 

LossatlOO^,  H'-'O   '.. 0.275 

Loss  above  100°,  H-O 1. 17'J 

Silica,  SiO  40.  (Vu 

Phosphoric  acid,  PW  0.232 

Titanic  acid,  TiO- 1.721 

Alumina,  Al-O1 14.r,s:i 

Ferric  oxide,  Fe-O3. 1.940 

Ferrous  oxide,  FeO 9.  632 

Manganous  oxide,  MnO   0.  154 

Lime.  CaO 10.091 

Magnesia,  MgO f>.  093 

Soda,  NaK) 4.597 

Potassa,  K'O 0. 1!)9 

Total 100.482 

The  atomic  ratio  deduced  from  this  analysis  is  H2  :  R"  :  fivl  :  Si  — 
0.162  :  1.116  :  0.935  :  3.272. 

No.  11,  Knoxville,  appears  microscopically  a  green,  much-altered 
sandstone,  intersected  by  numerous  minute  veins  of  white  mineral.  Under 
the  microscope  it  is  found  to  be  a  holocrystalline  pseudodiabase  consider- 
ably decomposed.  The  feldspars  are  in  part  granular,  but  chiefly  lath- 
shaped  crystals  from  O.lmm  to  0.4mm  in  length.  They  are  mostly  clouded  by 
very  small  interpositions.  The  greater  part  show  polysynthetic  structure, 
and  the  highest  angles  of  extinction  found  were  from  16°  to  18°  on  each 
side  of  the  twinning  plane.  The  fine  grain  of  the  rock  and  the  presence 
of  much  epigenetic  chlorite  make  separation  difficult.  It  was  found,  how- 
ever, that  the  last  precipitate  fell  at  a  density  of  2.63,  and  there  is  there- 
fore little  orthoclase,  if  any,  in  the  rock.  The  feldspar  must  be  chiefly,  if 
not  wholly,  oligoclase. 

The  veins  in  this  slide  are  filled  for  the  most  part  with  beautiful 
prismatic  crystals  of  plagioclase  mixed  witli  calcite.  The  augite  occurs 
as  imperfect  prismatic  crystals  and  grains,  either  included  in  the  feldspars 
or  between  the  crystals  of  the  latter.  Its  color  is  very  faint ;  it  is  not 
dichroitio  and  gives  characteristic  extinctions.  The  large  amount  of  chlo- 


PSEUDODIABASE.  99 

rite  appears  due  to  the  decomposition  of  the  augite.  Zoisite  is  not  very 
abundant  in  this  slide,  but  is  present  in  characteristic  prisms.  Ilmenite 
and  leucoxene  are  frequent. 

Xo.  36,  Sulphur  Bank,  is  a  dark-green,  fine-grained,  crystalline  rock, 
in  which  feldspars  and  bisilicates  can  be  seen  with  the  naked  eye.  Under 
the  microscope  all  the  feldspars  appear  to  be  twinned  and  those  which 
are  favorably  placed  for  examination  give  angles  of  extinction  appropriate 
to  oligoclase.  The  slide  contains  a  little  quartz.  The  pyroxene  is  mostly 
in  the  form  of  small  grains,  but  there  are  some  larger  crystals  giving  the 
angle  of  extinction  of  augite.  The  mineral  is  almost  colorless.  The  slide 
also  contains  one  hornblende  prism.  Titanic  iron  and  unquestionable  tran- 
sitions from  this  to  titanite  are  common. 

This  slide  shows  notable  secondary  changes.  Uralitization,  which  is 
so  common  in  the  pseudodiabases,  is  here  entirely  absent)  The  augite  de- 
composes directly  into  serpentine  and  chlorite,  both  of  which  are  abundant. 

A  complete  analysis  of  this  rock  was  made.  The  composition  is  ex- 
tremely similar  to  that  of  No.  21,  Coast  Ranges,  given  above: 

Loss  at  100°,  H-O 0.389 

Loss  above  100°,  H-O 2.965 

Silica,  SiO- 51.278 

Phosphoric  acid,  P2OS 0.131 

Titanic  acid,  TiO2 1.330 

Alumina,  A1203 15.048 

Ferric  oxide,  Fc-O3 2.415 

Ferrous  oxide,  FeO 8.014 

Nickel  oxide,  NiO 0.098 

Manganous  oxide,  MnO 0.251 

Lime,  CaO 7.079 

Magnesia,  MgO C.  069 

Soda,  NaaO 4.433 

Potassa,  K-O 0. 123 


Total 99.623 

The  atomic  ratio  deduced  from  this  is  H2  :  11"  :  Svi  :  Si  =  0.373  :  0.931 
:  0.974  :  3.419. 


PSKUDODIORITE. 


The  pseudodiabase  passes  by  transition  into  gabbroitic  modifications 
on  the  one  hand  and  into  pseudodiorite  on  the  other.     There  is  no  general 


100  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

and  characteristic  distinction  between  pseudodiorite  and  pseudodiabase,  as 
seen  under  the  microscope,  excepting  the  character  of  the  bisilicate,  and 
it  is  only  when  the  bisUicate  is  unusually  abundant  that  the  two  rocks  can 
be  told  apart  without  the  microscope. 

An  interesting  pseudodiorite  is  No.  179,  Knoxville.  This  is  a  fine- 
grained, crystalline,  dark-green  rock,  in  which  amphibole  is  visible  macro - 
scopically.  Under  the  microscope  it  is  seen  that  the  rock  is  a  porphyry, 
containing  large  grains  of  hornblende  5:i  a  fine-grained,  colorless  grouncl- 
imass.  When  well  exposed  this  groundmass  shows  a  faint  net- work  of  green- 
ish lines,  which,  judging  from  the  form  of  the  net,  represents  the  outlines 
of  the  original  clastic  structure.  Cracks  also  intersect  the  groundmass, 
and  these  often  radiate  from  the  porphyritic  hornblendes  in  a  very  peculiar 
manner,  as  if  the  hornblendes  had  expanded  forcibly  while  forming.  The 
groundmass  is  very  fine-grained,  the  individuals  ranging  from  0.01mm  down- 
wards. 

Polysynthetic  microlites  were  not  detected,  but  the  material  precisely 
resembles  that  in  another  rock  from  the  same  district  (No.  105,  Knoxville), 
which  was  isolated  and  found  to  have  a  specific  gravity  of  2.64,  to  contain 
59.14  per  cent,  of  silica,  and  to  correspond  qualitatively  to  andesine  in 
composition. 

The  hornblende  is  of  a  brownish-green  color  and  forms  grains  reach- 
ing half  a  millimeter  in  length.  In  the  hornblendes  are  small  shreds  and 
patches  of  glaucophane.  In  other  pseudodiorites  (for  example,  No.  183, 
Knoxville),  there  is  more  glaucophane  and  single  crystals  of  amphibole 
may  be  seen,  blue  at  one  end,  green  at  the  other,  and  of  intermediate  tints 
in  the  middle.  The  glaucophanic  pseudodiorites  form  a  link  between  the 
granular,  crystalline  rocks  and  the  glaucophane  schists.  This  slide  shows 
ilmenite  and  leucoxene,  but  no  zoisite  was  detected.  There  runs  through 
the  slide  a  vein  which  is  filled  with  chlorite  and  a  colorless  mineral  of  un- 
certain character. 

The  hornblende  in  the  pseudodiorites  is  sometimes  so  abundant  as  to 
form  much  the  greater  part  of  the  rock,  which  may  then  be  considered  as 
an  amphibolite.  One  of  the  best  examples  of  this  kind  is  No.  56,  Knox- 
ville. It  is  composed  almost  exclusively  of  long,  slender,  greenish  crystals 


GABBROS.  101 

of  actinolite  in  nearly  parallel  arrangement,  giving  the  mass  a  schistose 
character.  The  microscope  shows  a  little  white  mica,  chlorite,  and  serpen- 
tine in  the  rock.  Included  in  the  actinolite  are  also  grains  of  titanite,  brown, 
somewhat  pleochroitic  prisms  of  rutile,  nnd  small  zircons.  Long,  thin,  dark 
inclusions,  arranged  parallel  to  the  cleavage  of  the  amphibole,  are  perhaps 
also  rutile.  The  following  analysis  shows  the  composition  of  this  rock: 

Loss  at  100°,  H-O 0.008 

Loss  above  100°,  H-'O .'. 0.910 

Silica,  SiO2 50.  4;i7 

Alumina,  Al'O" 8.183 

Chromic  oxide,  Cr!O' 0.480 

Ferric  oxide,  Fe-O1 1.059 

Ferrous  oxide,  FeO 6. 285 

Manganous  oxide,  MnO 0.213 

Lime,  CaO 11.550 

Magnesia,  MgO 17.628 

Soda,  Na-O • 2.982 

Potassa,  K-O 0.503 


Total 100.304 

The  atomic  ratio  deducible  from  this  analysis  is  H2  :  H"  :  Rvl  :  Sir: 
0100  :  l.f>73  :  0.539  :  3.362. 

GABBROITIC    PSKUDODIABASK. 

While  a  tendency  to  the  development  of  the  clinopinacoidal  cleavage 
of  the  pyroxenes  of  the  pseudodiabase  has  been  already  noted,  character- 
istic diallage  is  somewhat  rare.  One  occurrence  is  known  on  Bagley  Creek, 
at  Mt.  Diablo,  the  great  mass  of  which  is  composed  of  zoisite-pseudodiabase 
and  phthariites.  It  is  a  dark-green  rock,  composed  of  granules  of  from  one 
to  two  millimeters  in  diameter.  Fresh  feldspar  and  the  grayish-green,  al- 
most metallic  luster  of  the  diallage  cleavage  surfaces  are  visible  with  the 
naked  eye. 

Under  the  microscope  the  diallage  is  monochroitic,  nearly  colorless, 
and  carries  inclusions  in  the  direction  of  the  best  cleavage.  The  slide  con- 
tains a  little  uralitic  hornblende.  In  a  few  places  a  decomposition-product, 
similar  in  appearance  to  the  ferruginous  cement  of  the  sandstones,  appears 
to  have  formed  from  the  diallage.  The  feldspars  are  clear  and  give  extinc- 
tions jis  high  as  30°  on  each  side  of  the  twinning  plane,  indicating  the  pres- 
ence of  labradorite. 


102  QUICKSILVER  DEPOSITS  OF  THE   I'ACIFIC  SLOPK. 

The  hand  specimens  of  this  rock  do  not  greatly  resemble  eruptive 
masses  and  the  nature  of  the  occurrence  clearly  indicates  their  metamorphic 
character,  but  the  slide  is  indistinguishable  from  thin  sections  of  eruptive 
gabbros. 

There  appears  to  be  no  reason  to  consider  the  above-described  rock 
as  anything  more  than  a  variety  of  the  pseudodiabase.  A  similar  rock 
is  found  at  the  Great  Western,  and  at  New  Almaden  a  gabbro  occurs  as 
pebbles,  apparently  derived  from  the  mountains  to  the  south. 


GLAUCOPIIAXE   SCHISTS. 


character. — Accompanying  the  granular,  holocrystalline  metamorphics,  in 
much  smaller  quantities  than  these,  are  somewhat  schistose  rocks,  which 
are  sometimes  evidently  micaceous  and  sometimes  appear  to  the  naked  eye 
chloritic.  All  of  these  are  found  to  carry  glaucophane,  iisually  accompa- 
nied by  zoisite  and  mica.  Some  of  them  are  macroscopically  indistinguish- 
able from  specimens  from  Syra.  They  are  so  related  structurally  to  the 
granular  rocks  as  to  show  them  to  be  members  of  the  same  series,  and,  as 
has  been  shown,  glaucophane  and  zoisite  both  occur  in  the  granular  rocks. 
It  is  worthy  of  note  that  the  plagioclase  of  the  granular  rocks  and  the  glau- 
.  cophane  of  the  schists  each  imply  the  presence  of  sodium  in  the  solutions, 
by  which  metasomatosis  of  the  sandstone  series  was  effected.  The  zoisites 
also,  at  least  in  part,  contain  alkalis.  Though  glancophane  rocks  are  not 
infrequent  in  the  Coast  Ranges  they  usually  occur  only  in  small  patches, 
and  it  is  seldom  possible  to  trace  them  to  their  unaltered  form.  At  Mt. 
Diablo,  however,  they  certainly  pass  over  into  slightly  altered  shales,  and 
there  is  also  evidence  elsewhere  that  the  schistose  structure  is  an  original 
feature,  not  a  result  of  metamorphism.  The  predominant  cleavage  in  these 
schists  is  marked  by  a  prevailing  similarity  of  direction  of  the  glaucophane 
prisms  and  mica  foils,  although  by  no  means  all  of  the  crystals  of  either 
mineral  are  similarly  placed.  The  structure  and  association  of  minerals 
will  best  be  described  by  examples. 

Examples. — No.  31,  Sulphur  Bank,  is  a  schistose,  gneiss-like  rock,  in 
which  layers  of  greenish  mica,  in  small  foils,  traverse  a  fine-grained, 
reddish  or  greenish  gray,  granular  mass.  Bluish-gray  grains  of  glauco- 


(iLAlJCOIMfANU  H01I1ST.  103 

phane  are  also  macroscopically  visible.  Under  the  microscope  a  great 
portion  of  the  rock  is  seen  to  be  made  up  of  interlocking  grains  of  quartz 
and  nnstriated  feldspar.  In  the  Thoulet  solution  a  considerable  amount  of 
feldspathic  material  floats  at  .'5.59,  and  this-gives  a  strong  potash  reaction, 
showing  that  the  material  is  at  least  in  part  orthoclase.  Higher  specific 
gravities  and  chemical  tests  show  that  plagioclase  is  also  present.  The  slide 
contains  a  number  of  large  glaucophane  crystals,  some  of  them,  which  arc 
cut  across  the  principal  axis,  exhibiting  the  characteristic  amphibole  prism 
and  cleavage.  The  optical  properties  are  as  described  on  a  previous  page. 
There  are  few  microlites  of  glaucophane. 

Embedded  in  the  mass  of  feldspar  and  quartz  are  numerous  green 
hexagonal  foils,  which  give  the  optical  reactions  of  mica  and  are  soluble  with 
difficulty  in  hot  sulphuric  acid.  The  mineral  is  probably  a  biotite.  White  ' 
mica  is  also  present.  The  scales  of  this  mineral  cannot  well  be  separated, 
but  in  a  similar  rock  (No.  117,  Coast  Ranges)  white  mica  is  present  in  foils  of 
considerable  size,  which  can  be  separated.  They  show  a  large  angle  between 
the  optical  axes,  and  are  therefore  probably  muscovite.  Zoisite  is  abun- 
dant in  No.  31,  in  well  developed,  pointed  prisms  with  terminal  faces.  It  is 
greenish  and  slightly  dichroitic,  which  is  unusual.  The  slide  contains  a  few 
garnets  and  much  titanite.  Some  well  developed  rhombs  of  the  latter  min- 
eral include  ilmenite  grains.  Apatites,  zircons,  and  a  little  chlorite  con- 
nected with  the  biotite  were  observed.  In  the  groundmass  are  groups  of 
long,  colorless,  radiating  fibers,  which  appear  to  extinguish  light  in  the 
direction  of  the  main  axis  and  when  densely  massed  give  very  vivid  inter- 
ference colors.  These  properties  correspond  to  fibrolite,  and,  did  these 
needles  occur  in  a  true  gneiss,  instead  of  in  a  Cretaceous,  metamorphic  rock, 
no  hesitation  would  be  felt  in  identifying  them  as  such.  Under  the  cir- 
cumstances and  in  the  absence  of  opportunity  for  determining  their  specific 
gravity,  it  is  not  safe  to  pronounce  on  their  composition. 

No.  147  corresponds  in  some  particulars  to  the  rock  just  described; 
brilliant,  brown  biotite,  however,  with  characteristic  interference  figure, 
replaces  the  muscovite,  and  a  small  portion  of  the  feldspar  shows  striations. 
The  glaucophane  is  in  all  respects  similar.  Apatite  is  present,  but  zoisite 
could  not  bo  identified  with  cnrtaintv. 


104 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


No.  98,  Sulphur  Bank,  is  a  greenish-gray,  schistose  rock,  consisting 
chiefly  of  glaucophane  and  zoisite.  The  latter  occurs  in  imperfect  prismatic 
crystals,  with  a  maximum  length  of  from  O.lmm  to  0.2mm.  The  prisms  show 
longitudinal  furrows.  The  zoisite  is  distinct!}7  dichroitic  and  has  a  faint 
olive-green  tint  when  the  prisms  are  parallel  to  the  principal  section  of  the 
nicols.  Sections  perpendicular  to  the  main  axis  are  square,  often  with  one 
truncated  corner.  The  extinctions  are  normal  and  the  colors  of  interference' 
are  gray  to  yellow  in  the  prisms,  but  more  vivid  in  granular  aggregates. 
The  angle  of  the  optical  axes  appears  to  be  large. 

Glaucophane,  in  needles  and  long,  imperfect,  nearly  parallel  prisms, 
gives  the  rock  its  cleavage.  Quaiiz,  albite,  muscovite,  and  titanite  arc 
present. 

•         The  rock  was  reduced  to  a  grain  of  one-third  of  a  millimeter,  and  sep- 
arated by  the  Thoulet  method  with  the  following  result: 


Specific 
gravity  of 
solution. 


3.22 
3.21 
3.10 
3.03 
2.  04 
2.56 
2.C8 


diameter  if]  recipit;ito. 


Small  quantities  of  opacito  and  titanite. 

Tolerably  pure  zoisite,  which  was  repeatedly  purified.     For  anal\  KM,  j*ce  p.  71). 

No  precipitate.    Glaucopliane  suspended. 

Glaucophane,  with  some  zoisite  and  muscovite. 

Nearly  pure  quartz. 

A  small  quantity  of  feldspar,  probably  albite. 

A  very  few  grains  of  a  colorless,  indeterminable  imru'r.  1. 


A  complete  analysis  of  the  rock  gave  the  following  result: 

Loss  at  1CO°,  H-O 0.000 

Loss  above  100°,  II-O 3.842 

Silica,  SiO3 49.680 

Phosphoric  acid,  P205 0.206 

Titanic  ocid,  TiO- 1.305 

Alumina,  AW 13.603 

Ferric  oxide,  Fc5O3 1.  8C2 

Ferrous  oxide,  FcO 8.606 

Manganoiis  oxide,  MuO   0.038 

Lime,  CaO 10. 9G? 

Magnesia,  MgO 6. 203 

Soda,  Na'O 3.091 

Potassa,  K=O 0. 11U 


Total W.584 


DECOMPOSITION  OF  THE  ROOKS.  105 

Tho   atomic   ratio   dedueible   from   this   analysis   is    IP  :  R"  :  SVI  :  Si 
=  0.427  :  1.04-1  :  0.868  :  3.312. 

DECOMPOSITION   OF   THK   CRYSTALLINK   ROCKS. 

character. — All  the  crystalline  rocks  iu'Q  often  found  in  a  more  or  less 

J 

advanced  stage  of  decomposition.  Besides  serpentinization,  which  will  be 
treated  in  a  separate  section  of  this  chapter,  there  have  been  other  processes 
lit  work,  particularly  the  epigenetio  formation  of  uralite,  chlorite,  and  nac- 
rite.  Though  it  is  difficult  to  make  out  the  precise  relation  of  these  trans- 
formations to  serpentinization,  reasons  are  given  elsewhere  for  believing 
them  to  belong  substantially  to  a  different  period  from  the  serpentinization. 
The  conversion  of  augite  to  uralite  is  common  in  the  augitic  metamor- 
phics  and  ordinarily  presents  no  peculiarity.  As  has  already  been  men- 
tioned, however,  brown  hornblende  and  augite  are  in  one  case  so  associated 
as  to  suggest  epigenesis,  though  it  is  believed  that  the  phenomenon  is  really 
one  of  envelopment.  Chlorite  forms  directly  from  brown  hornblende,  ural- 
ite, augite,  and  garnet.  It  is  also  not  infrequently  found  in  needles  in  feld- 
spar in  such  a  way  as  to  suggest  the  supposition  that  it  may  be  a  result  of 
the  attack  of  feldspar  by  solutions.  Epidote  is  found  much  less  abundantly 
than  it  often  is  in  eruptive  rocks.  Its  relations  to  chlorite  are  referred  to 
under  the  description  of  epidote.  In  a  single  pseudodiabase  from  New 
Almaden  somewhat  irregular,  six-sided  scales,  showing1  radial  striation  and 
remaining  sensibly  dark  between  crossed  nicols,  occur  in  the  feldspars  and 
are  supposed  to  be  nacrite.  Less  well  developed  flakes  of  a  similar  sub- 
stance are  common  in  other  rocks,  but  no  considerable  quantity  of  anything 
corresponding  to  the  descriptions  of  kaolin  has  been  detected.  Iron  oxides, 
carbonates,  and  leucoxene  (probably  titanite)  are  abundant. 


1'IITHANITKS. 


character — Associated  with  the  sandstones  of  every  group  in  the  Coast 
Ranges  is  more  or  less  shale,  which,  however,  seldom  forms  any  large  por- 
tion of  the  exposures.  Some  of  these  shales  do  not  effervesce  with  acid, 
and  analysis  shows  that  these  contain  extremely  little  lime  or  magnesia ; 
others  are  composed  to  a  large  extent  of  carbonates.  The  shales  of  the 


106  QUICKSILVER  DEPOSITS  OF  TIIK  PACIFIC  SLOPE. 

Knoxville  group  are  sometimes  unaltered,  but  more  frequently  silicified  to 
chert-like  masses  of  green,  brown,  red,  or  black  colors,  intersected  by  in- 
numerable veins  of  silica.  These  highly  altered  shales,  when  very  thin- 
bedded,  break  into  parallelopipedic  fragments,  but  where  the  beds  reach  a 
thickness  of  half  an  inch  or  more  there  is  a  decided  tendency  to  conchoidal 
fracture.  The  green  varieties  are  infusible  before  the  blow-pipe,  while  the 
brown  specimens  are  more  or  less  fusible.  The  only  essential  difference 
appears  to  be  in  the  state  of  oxidation  of  the  iron,  which  is  partially  solu- 
ble in  the  reddish  rocks.  The  most  convenient  name  for  these  rocks  is 
phthanite,  introduced  by  Haiiy  to  designate  quartzose,  argillaceous  rocks 
with  a  compactly  schistose  structure.  This  term  has  sometimes  been  em- 
ployed in  a  more  special  sense  to  denote  siliceous  beds  intercalated  in  lime- 
stone, but  this  limitation  will  not  be  adopted  here.1 

PhthanJtes  occur  in  all  the  metamorphic  districts  of  the  Coast  Ranges, 
and,  though  the  quantitative  proportion  which  they  bear  to  the  other  rocks 
is  not  great,  the  marked  contrast  between  them  and  the  surrounding  masses 
gives  them  prominence.  Geologically  it  is  impossible  to  dissociate  the 
phthanites  from  the  altered  sandstones,  holocrystalline,  metamorphic  rocks, 
and  serpentine.  All  of  these  rocks,  with  transitional  varieties,  are  found 
together  and  are  often  mingled  in  the  confused  masses  of  rubble  which 
have  sometimes  resulted  from  intense  dynamical  action.  The  metamorphic 
character  of  the  phthanites  is  manifest  both  from  their  structure  and  from 
the  transitions  —  which  exist,  for  example,  at  Venado  Peak,  New  Idria  —  into 
ordinary  shales.  Under  the  microscope,  also,  the  most  highly  indurated 
specimens  are  found  to  contain  fossils 

The  peculiar  habitus  of  the  phthanites  appears  to  arise  from  the  fact 
that  the  shales  have  offered  great  resistance  to  serpentinizatibn,  although 
they  have  not  wholly  escaped  this  alteration,  while  they  were  admirably 
adapted  both  to  silicification  and  to  the  display  of  a  net-work  of  quartz 
veins. 

The  mass  of  the  phthanites  as  seen  under  the  microscope  consists 
mainly  of  fine-grained,  crystalline  silica,  occasionally  accompanied  by  a 


1  Compare  Mr.  Renard's  Recherches  lithologiques  snrles  ]>litl)aiiit<\s  du  ciilciiirn  r;irl>oiiil7>n>  do  Be]. 
gi<ine:  Bull.  Acad.  roy.  Belgique,  vol.  46,  is?*. 


1'HTHAMTK.  107 

little  opal.  Mixed  with  the  silica  is  ferric  oxide  or  ferric  hydrate,  some- 
times in  very  uniform  distribution  and  again  in  patches  or  streaks.  The 
iron  oxide  is  somewhat  translucent  and  is  soluble  in  dilute  chlorhydric  acid 
with  a  yellow  color.  The  mass  is  ordinarily  intersected  by  extremely  nu- 
merous quartz  veins.  These  are  seldom  more  than  0.5miu  in  thickness,  while 
the  thinnest  are  often  visible  under  the  microscope  as  mere  white  lines  of 
insensible  width.  The  veins  are  usually  continuous  across  the  slide,  but 
may  sometimes  be  observed  pinching1.  When  this  is  the  case  the  fissure 
narrows  very  gradually  as  the  point  is  approached,  as  is  the  case  with 
fissures  of  all  sizes  in  all  rocks.  There  are  nearly  always,  if  not  invaria- 
bly, two  sets  of  fissures  in  the  phthanites,  crossing  each  other  at  a  high 
angle,  and  all  the  phenomena  are  precisely  similar  to  those  accompanying 
torsional  fracture  as  investigated  by  Mr.  Daubrt'e.1  Small  dislocations  of 
course  inevitably  accompany  fractures  of  this  description. 

The  veins  are  principally  filled  with  crystalline  quartz  in  which  fluid 
inclusions  have  not  been  detected  with  certainty.  Besides  the  quartz,  how- 
ever, there  are  often  found  numerous  prisms  of  zoisite.  In  the  larger  veins 
these  are  usually  arranged  along  the  walls,  from  which  they  appear  \o  have 
grown.  In  the  smaller  veins  long,  jointed  prisms,  such  as  are  illustrated  in 
Fig.  1  (page  78),  often  lie  parallel  to  the  strike  of  the  vein.  The  zoisite  in 
these  rocks  is  thoroughly  characteristic,  showing  jointing  of  the  crystals, 
fluted  surfaces,  tolerably  high  refraction,  yellow  interference  colors,  and 
extinction  strictly  parallel  to  the  main  axis,  as  given  under  the  description 
of  the  mineral.  The  prisms  are  too  much  fluted  to  give  good  cross-sec- 
tions. In  its  mode  of  occurrence  it  differs  somewhat  from  the  zoisite  of 
the  sandstones,  for,  while  in  the  latter  it  is  usually  embedded  in  products  of 
metasomatosis,  in  the  phthanites  it  occurs  in  an  infiltrated  mass  and  appears 
to  result  from  a  reaction  between  the  silica  and  the  shale.  In  certain  spots 
the  silica  seems  to  have  eaten  into  the  walls  of  the  veins,  and  here  zoisite 
is  especially  abundant.  Sometimes,  on  the  other  hand,  the  veins  show  no 

1  Mr.  Daubrde  has  written  several  papers  on  fractures  in  rocks,  which  are  illustrated  by  experi- 
ments. They  will  be  found  in  the  Bull.  Soo.  ge"ologique  France,  1878-1879,  1881-18K.',  and  in  the  Anuu- 
aire  du  club  alpiu  francais,  1881,  1882.  The  figures  of  the  second  plate  in  the  first  paper  in  the  latter 
journal,  which  represent  the  fissures  produced  by  torsion  in  glass  plates,  might,  so  far  as  I  could  tell, 
be  from  photographs  of  somewhat  weathered  phthanites  from  the  Coaei  Ranges. 


108  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

zoisite.  It  is  probable  that  only  calcareous  spots  or  areas  in  the  .shales 
have  yielded  zoisite. 

The  occurrence  of  zoisite  in  the  fossiliferous  phthanites,  associated  as 
they  are  with  the  other  metamorphic  rocks,  is  very  significant  and  affords 
ample  justification,  if  this  were  needed,  for  regarding  zoisite  as  indicative 
of  the  metamorphic  character  of  all  the  rocks  in  the  Coast  Ranges,  in  which 
it  is  found  under  conditions  excluding  the  supposition  that  it  is  of  later 
formation  than  the  accompanying  minerals. 

In  the  mass  of  the  phthanites  included  between  the  quartz  veins 
remains  of  clastic  structure  are  often  visible,  especially  in  reflected  light. 
The  most  interesting  constituents  of  foreign  origin  are  round  spots,  which 
often  retain  evidences  of  organic  character.  Prof.  Joseph  Leidy,  at  my 
request,  has  examined  some  of  the  thin  sections  containing  such  spots, 
which  he  regards  as  probably  foraminiferous  shells. 

SERPENTINE. 

Mincraiogicai  character.  —  Serpentine  occurs  in  irregular  areas  throughout  the 
quicksilver  belt,  sometimes  in  comparatively  pure  masses  and  sometimes  as 
one  of  the  mineral  constituents  of  altered  sandstones  and  granular,  meta- 
morphic rocks.  No  exact  estimate  can  be  made  of  the  area  covered  by 
serpentine,  but  it  is  believed  to  occupy  not  less  than  1,000  square  miles 
between  Clear  Lake  and  New  Idria.  As  important  results  concerning  tt,e 
genesis  of  serpentine  and  the  history  of  the  rocks  with  which  it  is  connecteJ 
depend  upon  the  correctness  of  its  identification,  a  somewhat  detailed  de 
scription  of  its  chemical  and  physical  properties  is  essential  to  the  purposes 
of  this  investigation.  In  studying  the  collections  it  was  found  that,  although 
the  physical  properties  of  the  hand  specimens  seemed  in  many  cases  clearly 
indicative  of  their  mineralogical  character,  the  microscope  revealed  such 
great  differences  in  the  optical  behavior  of  the  substance  supposed  to  be  ser- 
pentine as  to  lead  to  a  doubt  of  its  mineralogical  homogeneity.  Such  differ- 
ences might  indeed  be  anticipated  from  the  statements  in  previous  publica- 
tions. Prof.  J.  D.  Dana1  says  that  in  serpentine  when  pseudomorphic  there 
is  no  polarization  or  only  irregular  colors  as  in  amorphous  or  cryptocrys- 


1  System  of  Mim-mln^y,  ]>.  Ifil. 


VARIETIES  OF  SERPENTINE.  109 

talline  'substances,  but  that  colors  are  usually  apparent  in  laminated  and 
fibrous  varieties.  According  to  Professor  Rosenbusch1  the  distribution  of 
color  in  polarized  light  varies  with  the  structure,  here  in  patches,  there 
sinuous  or  in  parallel  streaks.  Especially  where  the  structure  is  fibrous 
and  chrysotile-like  the  change  of  colors,  though  not  strong,  is  unmistakable. 
Where  the  structure  permits  of  optical  examination  the  substance  is  found 
to  polarize  light  more  or  less  strongly  and  to  be  biaxial,  with  a  highly  varia- 
ble angle  between  the  optical  axes.  Messrs.  Fouque  and  Michel-Levy9  pro- 
nounce serpentine  a  colloid  mineral  without  any  proper  action  on  polarized 
light,  although  eminently  susceptible  of  presenting  the  optical  phenomena 
due  to  pressure.  Thus,  in  very  thin  sections  the  colors  of  polarization 
affect  very  pale,  bluish  tints  and  the  greater  part  of  the  substance  does  not 
react  between  crossed  nicols;  but  in  thick  slabs,  on  the  contrary,  the  colors 
are  often  vivid  and  brilliant.  On  the  other  hand,  foliaceous  varieties  of  the 
mineral  have  been  described  in  a  number  of  very  important  investigations 
of  the  serpentinoid  rocks  which  agree  with  Professor  Rosenbusch's  descrip- 
tion. Rocks  of  this  class  were  investigated  b}'  Mr.  von  Drasche  and  later 
by  Messrs.  Weigand,3  Becke,4  and  Hussak,5  all  of  whom  found  them 
mainly  composed  of  foliaceous,  distinctly  polarizing,  serpentine  varieties, 
such  as  bastite,  picrosmine,  and  metaxite.  Mr.  Hussak  has  described  this 
material  minutely  and  referred  it  to  antigorite.  According  to  this  authority 
it  has  considerable  pleochroism,  is  biaxial,  and  shows  blue-gray  tints  be- 
tween crossed  nicols.  The  analysis  is  that  of  a  somewhat  ferruginous  ser- 
pentine. Mr.  F.  Eichstiidt,8  in  discussing  the  antigoritic  serpentines  of 
northern  Sweden,  says  that  the  foliaceous  mineral  always  extinguishes  light 
when  the  cleavage  plane  coincides  with  a  principal  plane  of  the  nicols,  but 
that  when  the  cleavage  plan  is  horizontal  the  mineral  remains  dark  between 
crossed  nicols.  It  does  not  dichroise  sensibly.  The  interference  colors  are 
often  quite  vivid,  especially  in  the  coarser,  foliaceous  varieties,  but  are  fre- 
quently feeble  and  then  change  from  black  to  grayish  blue. 

1  Phys.  der  Mineral.,  p.  372. 

-Miu.  uiic.,  p.  441. 

3Tscherniaks  mineral.  Mittheil.,  vol.  3,  1875,  p.  183. 

4  Ibid.,  vol.  1,  1878,  p.  459. 

"Ibid.,  vol.  5,  1883,  p.  61. 

"Grol.  Fiireuingens  Stockholm  ForhftUtD.,  vol.  7,  1^4,  \>,  358. 


110  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

No  serpentine  which  remains  dark  between  crossed  nicols  is  found  in 
the  slides  from  the  Coast  Kanges,  and  excellent  cleavage  pieces  mounted 
in  balsam  give  biaxial  interference  figures  and  show  that  the  bisectrix  and 
the  plane  of  the  optical  axes  are  perpendicular  to  the  cleavage.  The  angle 
of  the  optical  axes  in  the  cases  thus  examined  is  not  very  small.  In  cross- 
section  the  extinction  always  takes  place  exactly  parallel  to  the  traces  of 
the  cleavage. 

The  colors  of  polarization  vary  greatly.  They  are  sometimes  confined 
to  different  shades  of  gray;  often,  however,  portions  of  slides  in  which  gray 
is  the  prevalent  color  show  dull,  yellow  tints,  and  in  rather  exceptional 
cases  reddish  tints  are  visible.  This  variation  is  frequent  in  slides  of  irre- 
proachable thinness  and  uniformity  and  does  not  depend  on  a  mere  differ- 
ence in  the  thickness  of  the  rock  section.  In  grinding  slides,  however,  it 
is  found,  as  would  be  supposed,  that  thick  masses  give  more  brilliant  colors 
than  thin  ones.  The  serpentine  usually  shows  the  merest  trace  of  dichroism, 
but  occasionally  a  very  perceptible  change  of  color  may  be  observed.  Only 
one  case  is  known  (No.  21,  New  Almaden)  where  a  remarkably  vivid -green 
serpentine  is  strongly  dichroitic  and  might  readily  be  confounded  with 
chlorite  unless  examined  between  crossed  nicols.  A  particularly  pure-look- 
ing, light-green,  marmolitic  serpentine  (No.  110,  New  Idria)  was  selected 
for  investigation.  A  complete  analysis  was  made,  with  the  following  re- 
sult : 

Silica,  SiO2 41.540 

Magnesia,  MgO 40.420 

Water,  IPO 14.175 

Alumina,  AK)1 2.480 

Ferrous  oxMe,  FeO 1.370 

Nickel  oxide,  NiO 0.040 


100. 025 


In  pure  serpentine  40.42  per  cent,  of  magnesia  corresponds  to  41.52 
per  cent,  of  silica.  It  appears,  therefore,  that  this  mineral  is  in  fact  a 
serpentine  comparatively  free  from  impurities  and  certainly  containing  no 
talc.  A  slide  was  also  cut  across  the  lines  of  structure  at  a  point  where 
the  specimen  appeared  extremely  uniform.  When  reduced  to  the  proper 
thinness  it  was  found  that  the  material  was  far  from  homogeneous.  A  por- 


TKSTS  OF  SERPENTINE. 


Ill 


tion  as  seen  under  the  microscope  appeared  absolutely  colorless  by  trans- 
mitted light,  while  the  remainder  was  of  yellowish  and  brownish  tints,  in 
spots  almost  opaque,  although  by  reflected  light  this  portion  retained  the 
pale  apple-green  color  of  the  hand  specimen.  The  more  highly  colored 
portions  of  the  slide  appear  to  be  clouded  by  the  presence  of  extremely 
tnicrocrystalline  particles,  perhaps  ferric  oxide;  but  these  particles  can 
hardly  have  any  direct  connection  with  the  more  brilliant  colors  of  polari- 
zation, for  the  portions  containing  them,  when  in  proper  relation  to  the 
nicols,  extinguish  light  almost  as  completely  as  the  others. 

The  entire  slide  has  a  banded  structure,  occasioned  by  the  arrange- 
ment of  fibers,  which  is  similar  in  character  to  that  most  usual  in  the  ser- 
pentine of  the  Coast  Ranges,  though  more  simple.  The  colorless  portion 
between  crossed  nicols  varies  from  black  to  light  gray,  and  the  brilliancy 
of  the  tints  increases  with  the  coloration,  being  yellow  in  certain  positions 
where  the  mass  is  lightly  colored  and  red  where  the  color  in  natural  light 
is  more  intense.  Precisely  the  same  relation  was  observed  in  slides  from 
other  localities  and  of  all  degrees  of  impurity. 

For  comparison  two  serpentines  from  Sulphur  Bank  (Nos.  786  and 
78e)  were  analyzed.  The  former  is  a  nearly  black,  impure-looking  mass, 
through  which  are  distributed  foils  similar  to  those  of  bastite,  excepting 
that  they  lack  the  metallic  luster.  Under  the  microscope  it  was  found  to 
contain,  besides  much  opacite,  serpentine  polarizing  in  yellow  tints,  though 
the  preponderating  mineral  shows  gray  interference  colors.  No.  78e  is  a 
light-green  mineral  from  the  same  locality  as  that  last  mentioned,  but 
much  purer  in  appearance. 


Dark 
serpentine. 

Light 
serpentine. 

Water  H20 

13  81 

14  16 

Silica  SiO2 

39  64 

41  86 

Alumina  APO3 

]  30 

0  69 

Chromic  oxide  Cr'-'O3 

0  29 

0  24 

7  76 

4  15 

Nickel  oxide  KiO 

0  33 

0.  12 

0  20 

37  13 

38  63 

100.  38 

99.93 

112  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

Both  specimens  are  evidently  essentially  serpentine  and  the  principal 
difference  is  in  the  amount  of  ferrous  oxide. 

While  the  comparison  of  these  analyses  with  the  slides  of  the  specimens 
from  which  they  were  made  might  seem  sufficient  to  test  the  relations  of  the 
chemical  and  optical  properties,  it  was  considered  best  to  pursue  the  subject 
somewhat  further,  because  minute  quantities  of  minerals  other  than  serpen- 
tine might  escape  detection  in  the  analysis.  It  seemed  especially  desirable 
to  establish  the  absence  of  talc  and  chlorite  from  the  substances  regardea 
as  serpentine  under  the  microscope.  Talc,  indeed,  could  not  escape  detec- 
tion in  flakes  or  grains  of  sufficient  size  to  be  submitted  to  optical  examina- 
tion, but  it  seemed  possible  that  intimate  mixtures  of  talc  and  serpentine 
might  be  present,  since  talc  is  known  to  occur  pseudomorphically  after  most 
of  the  minerals  which  have  been  shown  to  be  converted  into  serpentine  and 
after  many  more  besides.  Chlorite,  on  the  other  hand,  shows  a  considerable 
range  of  optical  properties  and  bears  some  resemblance  to  serpentine.  A 
series  of  simple  microchemical  tests  was  therefore  made  upon  the  slides  and 
specimens.  Serpentine  is  readily  attacked  by  warm  sulphuric  or  chlorhydric 
acid,  while  talc  is  decomposed  by  neither  and  chlorite  is  not  sensibly  at- 
tacked by  chlorhydric  acid.  It  was  shown  by  the  application  of  these  tests 
that  the  more  vividly  polarizing  serpentine  did  not  differ  in  chemical  behav- 
ior from  that  which  gives  only  gray  tints  between  crossed  nicols  and  that 
the  serpentine  in  the  altered  sandstones  behaves  exactly  like  the  massive 
serpentine.  The  optical  discrimination  between  chlorite  and  serpentine  was 
fully  confirmed,  and  no  trace  of  an  admixture  of  talc  in  the  serpentine  could 
be  detected.1 

'A  more  detailed  account  of  these  tests  may  possibly  bo  of  interest  to  some  readers,  since  the  pub- 
lished statements  as  to  the  behavior  of  these  minerals  are  in  part  not  quite  consistent  and  are  in  somt> 
cases  incomplete.  The  marmolitic  serpentine  of  which  an  analysis  has  been  given  was  found  to  be 
slowly  but  completely  decomposed  by  both  chlorhydric  and  sulphuric  acids  when  hot,  a  colloid  mass 
remaining.  A  slide  of  a  serpentine  from  near  Kuoxville,  which  showed  great  variation  in  the  colors  of 
polarization,  was  uncovered,  and  a  portion  which  gave  brilliant  tints  was  cut  oft' and  after  washing  in 
alcohol  was  heated  with  adrop  of  sulphuric  acid.  The  serpentine  was  completely  decomposed,  and  on 
partial  evaporation  prisms  of  magnesium  sulphate,  extinguishing  light  at  about  1G°,  and  later  hexag- 
onal uniaxial  scales  were  formed,  as  described  by  Professor  Haushofer  (Mik.  Reaetionen,  p.  90).  No 
other  salts  were  formed.  To  tost  the  serpentine  of  the  sandstones,  specimen  No.  57,  Clear  Lake,  wns 
selected,  because  it  contains  a  very  remarkable  pseudomorph.to  be  described  hereafter.  A  portion  of 
the  slide  was  selected  containing  a  quartz  surrounded  by  supposed  serpentine,  from  which  distinct, 
tooth-like  projections  penetrated  the  quartz.  A  perforated  cover  was  placed  over  this  spot  and  the 
balsam  washed  away  with  alcohol.  A  minute  drop  of  chlorhydric  acid  was  added  and  the  slide  heated 


IDENTITY  OF  THE  SERPENTINE.  113 

Talc  occurs  abundantly  in  the  metamorphic  areas  of  the  gold  belt, 
and  the  Survey  collections  contain  fine  specimens  from  that  region.  Ac- 
cording to  Mi-.  H.  G.  Hanks  it  is  also  found  at  two  or  three  localities  in  the 
Coast  Ranges.  Nothing  would  be  less_  surprising  than  the  discovery  in 
the  Coast  Ranges  of  serpentines  containing  flakes  of  talc  such  as  are  de- 
scribed by  Hussak,  but  this  combination  is  not  as  yet  known  to  occur 
The  analyses  also  exclude  deweylite  and  the  minerals  allied  to  it.  It  still 
rein? ins  possible  that  some  hitherto  unrecognized  mineral  closely  allied  to 
serpentine  enters  into  the  serpentinoid  mass,  but  the  gradation  of  prop- 
erties is  so  complete  that  this  seems  improbable.  The  variations  in  the  col- 
ors of  polarization  possibly  correspond  to  the  replacement  of  a  greater  or 
smaller  portion  of  magnesium  by  iron,  accompanying  which  there  is  likely 
to  be  a  change  in  the  angle  of  the  optical  axis.  This  angle  is  known  to 
vary  greatly  in  serpentines.  The  higher  color  in  natural  light  of  the  por- 
tions which  polarize  most  vividly  may  be  due  to  the  presence  of  ferric 
oxide  as  an  impurity.  The  association  of  a  partial  replacement  of  mag- 
nesium by  iron  and  a  separation  of  a  little  iron  oxide  would  not  be 
unnatural. 

The  mineral  described  as  antigorite  by  Mr.  Eichstadt  corresponds  in 
most  respects  to  that  described  by  Mr.  Hussak  and  others  and  to  the  ser- 

nearly  to  the  point  at  which  balsam  softens.  It  was  soon  found  that  the  serpentine  was  attacked. 
Fresh  portions  of  acid  were  added  from  time  to  time,  and  at  last  it  appeared  that  most  of  the  serpen- 
tine was  decomposed,  leaving  a  colloidal  mass.  Some  portions  in  immediate  contact  with  the  quartz 
grain  at  points  where  indentation  had  been  observed  appeared  to  be  entirely  converted  into  gelati- 
nous silica.  The  portions  which  were  only  partially  decomposed  almost  ceased  to  give  interference 
colors.  At  the  edge  of  the  acid  drop  upon  the  cover  there  formed  prisms  supposed  to  be  magnesium 
chloride,  giving  angles  of  extinction  of  over  30°.  The  solution  was  washed  off,  evaporated  on  a  second 
glass,  and  sulphuric  acid  added.  Prisms  giving  a  low  angle  of  extinction  formed  on  partial  evapora- 
tion. On  evaporating  until  fumes  of  sulphuric  anhydride  were  given  off,  the  hexagonal  scales  ap- 
peared, and  on  standing  a  few  moments  under  the  microscope  these  uniaxial  crystals  deliquesced.  The 
substance  under  examination  was  thus  certainly  a  magnesium  silicate,  and  not  a  talcose  mixture.  No 
other  crystals  made  their  appearance.  To  test  the  behavior  of  chlorite  a  pseudodiabase  (No.  CGft,  Sulphur 
Banl<)  was  selected  and  a  port  ion,  exposed  through  a  perforated  cover,  was  treated  witliehlorhydric  acid 
exactly  as  the  serpentine  had  been.  There  was  no  evidence  under  the  microscope  of  any  attack,  even 
al'ier  repeating  the  treatment,  several  times.  On  boiling  powder  from  the  same  specimen  in  chlorhydric 
iicid  it  was  found  that  the  chlorite  was  decomposed  when  the  acid  was  strong,  but  not  when  it  was 
dilute.  Both  magnesia  and  alumina  went  into  solution.  It  is  probable  therefore,  but  not  certain, 
that  this  chlorite  is  the  prochlorite  of  Dana.  The  highly  dichroitic  serpentine  (from  No.  21,  New  Al- 
maclen)  was  similarly  tested.  It  dissolved  in  warm,  dilute  chlorhydric  acid  in  the  thin  section  and 
when  the  pulverized  rock  was  boiled  in  strong  acid  magnesia,  but  no  sensible  quantity  of  alumina  was 
dissolved. 

MON  XIII 8 


114  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

pentines  of  the  Coast  Ranges.  The  Swedish  serpentine,  however,  is  stated 
to  be  sensibly  uniaxial,  which,  as  EichstJidt  remarks,  perhaps  means  only 
that  the  angle  of  divergence  of  the  optical  axis  in  this  case  is  extremely 
small.  It  seems  doubtful  whether  the  isotropic  mineral  referred  to  by 
Messrs.  Fouqu^  and  Michel-LeVy  can  lie  the  same  as  that  of  the  Coast 
Ranges, 

Microstructure  of  the  serpentine. Of     tll6     HUiny     Varieties     of     SerpeiltillO     wllicll 

have  received  separate'  mineralogical  names  several  are  recognizable  mac- 
roscopically  in  the  Coast  Ranges.  The  most  ordinary  is  the  massive 
green  mineral  of  different  shades  usually  intersected  by  highly  polished, 
curved  surfaces.  Such  rock  is  often  traversed  by  narrow  veins  of  white  or 
light-green,  fibrous  chrysolite.  Marmolitic  modifications  are  also  abundant 
In  many  of  the  serpentines  dark,  rounded  scales  are  frequent,  and  these 
often  show  in  some  lights  a  metallic  luster  answering  to  bastite  or  schiller- 
spar  in  part. 

Under  the  microscope  there  are  found  to  be  great  differences  in  the 
structure  and  arrangement  of  the  groups  of  fibers  or  scales  of  which  the 
serpentine  is  built  up.  These  are  sometimes  felted,  but  more  often  united 
in  bundles  of  approximately  similar  orientation.  In  the  latter  form  they 
answer  to  the  descriptions  of  antigorite.  Not  infrequently  groups  of  scales 
are  seen  under  the  microscope,  forming  masses  of  considerable  size,  in  which 
the  orientation  is  substantially  uniform,  and  in  sections  cut  obliquely  to  the 
predominant  cleavage  of  these  masses  a  fine,  yellow,  metallic  luster  is  some- 
times observable  once  in  every  complete  revolution.  It  is  uncertain  to 
what  this  luster  is  due.  These  masses  are  of  course  the  so-called  bastite 
scales.  There  are,  however,  many  other  aggregates  similar  in  all  respects 
excepting  that  they  show  no  metallic  luster.  The  groups  of  parallel  foils 
are  sometimes  separated  from  the  surrounding  mass  by  sharp  lines,  which 
in  no  case  present  crystallographic  outlines,  but  often  the  demarkation  is 
not  sharp. 

The  mineral  of  which  the  antigoritic,  chrysolitic,  and  bastitic  aggre- 
gates are  built  up  appears  to  be  essentially  the  same,  and  in  no  way  differ- 
ent from  that  of  the  felted  aggregates.  It  corresponds  well  to  the  descrip- 
tions of  antigorite,  but  answers  equally  well  in  all  essential  particulars  to 


STEUCTURE  OF  SERPENTINE. 


other  biaxial  varieties.  To  give  separate  mineralogical  names  to  mere  vari- 
ations in  the  arrangement  of  the  foils  of  a  foliaceous  mineral  seems  an  un- 
necessary complication  of  terminology,  nor  can  I  see  why  the  presence  of 
a  peculiar  luster  in  the  so-called  bastite~slfould  entitle  it  to  a  separate  name. 
Lustrous  labradorites  are  not  regarded  as  of  a  different  mineralogical  spe- 
cies from  labradorites  not  possessing  this  interesting  peculiarity.  It  thus 
appears  sufficient  to  classify  the  mineral  characterizing  the  serpentinoid 
rocks  of  the  Coast  Ranges  as  a  distinctly  biaxial  serpentine.  This  sepa- 
rates it  from  the  colloid  mineral  of  Messrs.  Fouque'  and  Michel-Ldvy  and 
from  the  possibly  uniaxial  antigorite  of  Mr.  Eichstadt.  The  necessity  of  a 
division  of  serpentine  into  more  than  these  three  mineralogical  varieties 
•seems  to  me  doubtful. 

Of  more  interest  and  importance  than  this  minute  classification  of  va- 
rieties is  the  structure  resulting  from  the  grouping  of  adjacent  microscopic 
aggregates.  Two  types  of  such  structure  are  known,  one  in  serpentine, 
produced  by  the  decomposition  of  olivine  and  representing  the  net-work  of 
cracks  of  the  parent  mineral,  usually  emphasized  by  the  presence  of  more 
or  less  opaque  matter.  The  other,  called  grate  structure,  was  first  studied 
by  Mr.  von  Drasche  in  Alpine  serpentines,  which  he  showed  to  be  derived 
from  augitic  and  amphibolic  rocks.  In  serpentines  of  this  class  the  foliated 
or  fibrous  mineral  is  arranged  in  narrow,  somewhat  sharply  limited  bands, 
which  are  nearly  straight,  though  often  discontinuous,  and  cross  one  another 
at  high  angles.  The  interstitial  spaces  are  filled  with  less  regularly  dis- 
posed material.  Mr.  F.  Becke  observed  the  same  structure  in  some  of  the 
Grecian  serpentines.  Mr.  Eichstadt  has  shown  that  in  some  of  the  Swe- 
dish serpentines  olivine  decomposes  into  serpentine,  exhibiting  this  grate- 
structure,  which  consequently  does  not  necessarily  represent  cleavages  in  a 
parent  mineral.  It  appears  to  me  probable  that  it  is  at  least  in  part  con- 
nected with  a  change  of  volume  attending  the  decomposition  of  the  min- 
erals from  which  the  serpentine  is  derived.  There  can  be  little  doubt,  how- 
ever, that  in  some  cases  the  position  of  the  grate-bars  has  been  influenced 
by  cleavages  in  the  original  mineral. 

In  the  serpentines  of  the  Coast  Ranges  the  olivinitic  net-structure  has 
not  been  detected,  nor  has  any  olivine  been  found  either  in  the  serpentine  or 


116  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

in  the  rocks  with  which  it  is  geognostically  associated.  Basalt,  it  is  true,  is 
common  in  some  districts  where  serpentine  abounds,  but  this  basalt  appears 
to  be  Post-Tertiary,  while  the  serpentinization  took  place  early  in  the  Cre- 
taceous. At  New  Almaden  also  pebbles  of  an  olivinitic  gabbro  have  been 
found,  which  probably  come  from  -the  neighborhood  of  Mt.  Bache.  This 
rock  does  not  occur  in  place  at  New  Almaden  and  is  very  fresh,  the  olivines 
showing  the  merest  traces  of  serpentine.  Macroscopically  it  strongly  re- 
sembles the  gabbros  from  Mt.  Diablo  and  the  Great  Western,  which  contain 
no  olivine.  It  is  not  impossible  that  some  of  the  serpentine  of  the  Coast 
Ranges  may  have  been  derived  from  an  olivinitic  rock  like  this,  but  if  so 
the  quantity  thus  formed  must  be  inconsiderable  compared  with  the  rest, 
since  no  trace  of  it  has  been  detected  elsewhere. 

The  greater  part  of  all  the  serpentine  shows  more  or  less  perfectly 
developed  grate-structure.  In  polarized  light  the  bars  usually  give  higher 
colors  of  interference  than  the  interstitial  matter,  but  this  relation  is  some- 
times reversed.  With  low  powers  a  single  bar  often  appears  to  extinguish 
light  simultaneously  all  over,  but  when  more  magnified  the  extinction  is 
seen  to  be  undulous  and  to  correspond  to  the  composite  nature  of  the  bars, 
which  are  made  up  of  foils  or  fibers  in  nearly  parallel  positions.  The  inter- 
stitial matter  often  gives  very  faint  and  undulous  colors  of  interference,  but 
has  not  been  found  isotropic.  The  more  regular  grate-structure  passes 
over  by  gradations  into  a  less  symmetrical  disposition,  and  felted  fibrous 
masses  are  not  uncommon  in  which  irregular  patches  show  slight  differences 
of  tint  both  in  polarized  and  in  natural  light. 

In  the  altered  sandstones  many  substances  are  of  course  included,  and 
in  some  cases  it  might  be  questioned  whether  these  rocks  should  be  classed 
as  serpentines  with  very  abundant  inclusions  or  as  sandstones  carrying" 
much  serpentine.  So,  too,  a  part  of  the  granular  metamorphics  contain  a 
very  large  amount  of  serpentine.  In  the  purer  serpentines  residual  grains 
are  not  abundant,  but  augite  may  sometimes  be  observed  with  cleavages 
parallel  to  the  grate-bars.  These  isolated  augite  grains  show  appropriate 
oblique  extinction  and  characteristic  colors  of  polarization  Chromic  iron 
is  a  common  inclusion  in  the  purer  serpentines,  but  by  no  means  invariably 
present.  It  is  of  a  deep,  dull-brown  color,  transparent,  monochroitic,  iso- 


DERIVATION  OF  SERPENTINE.  117 

tropic,  and  when  separated  gives  a  strong  chromium  reaction.  Numerous 
deposits  of  chromic  iron  intimately  associated  with  serpentine  are  known 
in  the  Coast  Ranges.  Magnetite  is  almost  always  present. 

The  origin  of  serpentine. —  Nocxtended  hisforical  account  of  the  views  held 
of  the  origin  of  serpentine  is  necessary  here.  The  present  investigation  is 
not  founded  on  any  similar  inquiry,  nor  do  I  suppose  that  all  serpentines 
in  other  regions  have  had  an  origin  similar  to  that  of  the  serpentine  of  the 
Coast  Ranges.  A  few  historical  notes,  however,  may  serve  to  refresh  the 
reader's  memory. 

The  occurrence  of  serpentine  in  dikes  led  to  its  classification  as  an 
eruptive  rock  by  the  earlier  geologists,  Avho  were  unaware  of  its  composi- 
tion, and  even  long  after  it  was  known  to  be  a  hydrated  mineral  there  are 
frequent  references  to  it  in  the  literature,  unaccompanied  by  any  qualifi- 
cation or  explanation,  in  which  it  is  classified  as  igneous.  The  close  and 
frequent  connection  between  gabbro  and  serpentine  led  L.  von  Buch,  in 
1810,  to  suppose  that  serpentine  was  a  dense  or  cryptocrystalline  form  of 
that  rock.  This  suggestion  is  interesting  as  showing  how  long  the  relation- 
ship of  the  rocks  has  been  recognized.  Direct  eruption  of  the  serpentines 
has  also  been  maintained,  in  a  modified  form,  by  more  recent  Italian  geolo- 
gists, who  suppose  outbursts  from  the  depths  of  the  earth  of  a  hydrated, 
magnesian  mud  which  consolidated  to  serpentine. 

In  1857  Dr.  T.  Sterry  Hunt  showed  that  when  a  mixture  of  magnesium 
carbonate  and  free  silica  is  heated  in  a  solution  of  alkaline  carbonate  a 
hvdrous,  magnesian  silicate  is  formed  and  the  alkaline  carbonate  is  re- 
generated. He  soon  afterwards  came  to  the  conclusion  that  this  process, 
though  locally  important,  would  not  explain  the  greater  part  of  the  occur- 
rences. In  1860  he  proposed  as  an  explanation  of  the  massive  serpentines 
the  reaction  between  the  soluble  silicates  of  lime  and  alkalis  from  decaying 
rocks  and  the  magnesian  salts  of  natural  waters.  Dr.  Hunt  admits,  however, 
that  serpentines  are  also  formed  by  epigenesis,  at  least  from  olivine  and 
enstatite.1  Dr.  Hunt's  view,  while  not  generally  accepted,  has  earnest 
advocates,  and  some  geologists  who  reject  this  theory  for  a  majority  of 
cases  believe  it  to  be  the  true  explanation  of  some  occurrences. 

1  Geol.  History  of  Serpentines,  1883,  §  117  ;  Origin  of  Crystalline  Rocks,  1834,  §  105. 


118  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  theory  of  the  origin  of  serpentine  most  usually  entertained  is  that 
it  results  from  the  alteration  of  other  minerals.  There  is  much  variation  of 
opinion,  however,  as  to  what  minerals  may  yield  serpentine.  Breithaupt  is 
said  to  have  been  the  first  to  detect  the  pseudomorphosis  of  serpentine 
after  hornblende  (1831)  and  to  infer  the  derivative  character  of  serpentine 
rocks.  Later,  serpentine  was  found  pseudomorphic  after  a  long  list  of  min- 
erals. Olivine,  brucite,  hornblende,  augite,  diallage,  chondrodite,  calcite, 
staurolite,  dolomite,  spinel,  chromite,  mica,  and  garnet  are  mentioned  by 
Prof.  J.  Roth.  Prof.  J.  D.  Dana  has  personally  identified  the  greater  part 
of  this  list  from  a  New  York  locality  arid  also  found  pseudomorphs  after 
apatite.1  Bischof,  Professor  vom  Rath,  and  others  have  shown  that  the 
conversion  of  feldspars  to  serpentine  is  probable,  and,  at  the  congress  of 
Bologna,  Professor  Szab6,  as  reported  by  Mr.  Lotti,  stated  this  as  his  opin- 
ion; but  I  am  not  aware  that  full  proof  of  this  change  has  ever  been- 
offered.  That  it  occurs  in  the  rocks  of  the  Coast  Ranges,  however,  seems 
beyond  doubt. 

In  1866  Professor  Sandberger2  and  in  1867  Professor  Tschermak3  studied 
the  transformation  of  olivine  rocks  to  serpentine,  though  neither  of  them 
asserted  that  olivine,  which  had  long  been  known  to  yield  serpentine,  was 
the  sole  source  whence  serpentine  was  derived.  "The  occurrence  of  em- 
bedded pyrrhotite,"  Professor  Sandberger  says,  "may  be  said  to  be  almost 
characteristic  of  the  serpentines  which  have  been  derived  from  hornblende 
rocks,  and  the  same  mineral  occurs  in  serpentines  which  are  derived  from 
diabases."  Professor  Tschermak,  though  stating  that  the  masses  known  as 
serpentine  and  schiller-spar  rocks,  which  he  had  had  an  opportunity  of  ex- 
amining, all  contained  olivine  as  a  principal  constituent,  also  remarks  that 
diallage  and  bronzite  grains  are  often  converted  into  schiller-spar  in  these 
rocks.  For  some  time  afterwards,  however,  there  was  a  strong  tendency  to 
ascribe  almost  all  serpentine  to  the  alteration  of  olivine,  which  was  found 
to  be  more  widely  distributed  and  mere  frequent  than  had  previously  been 
suspected.  Thus,  in  1873  Professor  Rosenbusch  wrote:  "It  appears  to  be 

1  Am.  Jour.  Sci.,  3d  series,  vol.  8,  1874,  p.  380. 

"Neues  Jahrbuch  fur  Mineral.,  18fifi,  p.  385;  ibid.,  1807,  p.  171. 

3  Ibid.,  1868,  p.  88. 


DERIVATION  OF  SERPENTINE.  119 

more  and  more  confirmed  by  the  investigations,  particularly  the  microscop- 
ical ones,  hitherto  made,  that  only  the  alteration  first  described  by  Sand- 
berger  from  olivine  rocks  to  serpentine  occurs  in  nature."  This  supposition, 
still  maintained  by  some,  was  soon  found  too  narrow  to  include  the  observed 
facts,  and  in  1877  the  same  distinguished  lithologist  acknowledged  that  ser- 
pentines or  serpentinoid  rocks  are  often  formed  from  pyroxene  and  amphi- 
bole.  In  view  of  the  earlier  literature  of  the  subject  it  seems  indeed  most 
improbable  that  the  serpentines  should  have  a  single  origin.  The  evi- 
dence of  actual  pseudomorphism  in  many  cases  was  sharply  questioned 
by  Scheerer  as  early  as  1846  and  later  by  Mr.  Delesse  and  Dr.  Hunt,  and 
no  doubt  some  cases  of  erroneous  determination  were  detected.  Many  in- 
stances, however,  stood  the  test  of  these  challenges.  All  the  more  important 
cases  have  also  been  reobserved  since  1867,  and  at  present  the  number  of 
occurrences  of  serpentine  shown  by  microscopic  research  to  be  derived 
from  rocks  containing  olivine  as  a  subordinate  constituent  only  or  not  at  all 
is  on  the  increase. 

According  to  the  law  of  thermochemistry,  in  any  mixture  of  substances 
capable  of  reacting  upon  one  another  the  resulting  compound  will  be  that 
whose  formation  is  attended  by  the  most  rapid  evolution  of  heat.1  Any 
given  mineral  will  therefore  be  produced  not  in  general  under  a  single  set 
of  conditions,  but  under  any  combination  of  the  whole  range  of  conditions  in 
which  the  formation  of  any  other  compound  would  be  attended  by  a  slower 
liberation  of  heat.  The  wider  the  range  of  these  conditions  the  commoner 
will  be  the  mineral,  and,  since  conditions  are  never  exactly  repeated,  the 
assertion  that  a  mineral  is  common  is  nearly  equivalent  to  the  statement 
that  its  formation  is  attended  by  the  most  rapid  evolution  of  heat  under 
diverse  sets  of  conditions.  Thus,  to  take  one  of  many  examples,  there  are 
Imt  few  ferruginous  compounds  which  in  weathering  or  in  roasting  do  not 
yield  hydrous  or  anhydrous  ferric  oxide ;  or,  in  other  words,  whether  the 
temperature  be  low  or  high,  the  formation  of  ferric  oxide  from  almost  num- 
berless compounds  of  iron  involves  the  liberation  of  heat  more  rapidly  than 
any  other  change.  That  serpentine  occurs  at  all  is  sufficient  evidence  that 
its  formation  is  attended  by  the  liberation  of  heat  under  certain  conditions. 

1  See  my  IIIIVHT,  A  m-\v  law  «(  i  licriiioi'lii-mistry :  Am.  Join-.  Si-i.,  M  serie*,  vol.  31,1886,  p.  WO. 


120  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

That  it  is  common  leads  to  the  belief  that  these  conditions  are  not  narrowly 
restricted,  and  this  is  confirms;!  by  the  fact  that  it  forms  in  the  olivines  of 
decomposing  basalts  and  also  in  limestone  beds.  It  is  no  more  surprising 
that  serpentine  should  form  from  many  and  different  minerals  or  under  dif- 
ferent circumstances  than  that  ferric  oxide  should  do  the  same. 

Bischof  held  a  similar  opinion,  calling  attention  to  the  fact  that  serpen- 
tine is  among  the  last  products  of  alteration  and  that  in  it  the  series  of 
processes  of  mineral  formation  and  alteration  have  nearly  reached  the  limit 
of  possibility.  Indeed  few  geological  chemists  would  be  inclined  to  dispute 
a  proposition  of  this  kind.  Dr.  Hunt,  for  instance,  who  points  out  the  anal- 
ogy between  the  modes  of  occurrence  of  serpentine  and  pinite,  says  of  the 
latter  that  its  constancy  of  composition  and  wide  distribution  show  it  to  be  a 
compound  readily  formed  and  of  great  stability.  Such  being  its  character, 
he  continues,  it  might  be  expected  to  occur  as  a  frequent  product  of  the 
aqueous  changes  of  other  and  less  stable  silicates,  and  "its  frequent  occur- 
rence as  an  epigenic  product  is  one  of  the  many  examples  to  be  met  with 
in  the  mineral  kingdom  of  the  law  of  the  '  survival  of  the  fittest.'"  That 
the  same  statement  applies  to  serpentine  is  manifestly  true. 

It  would  seem  to  follow  that  the  origin  of  serpentine  in  each  naturally 
defined  geological  area  requires  independent  investigation  and  that  the 
results  obtained  in  one  such  area  are  not  necessarily  applicable  to  others. 
It  will  be  seen  in  the  following  pages  that  the  observations  are  not  recon- 
cilable either  with  the  supposition  that  the  serpentines  of  the  Coast  Ranges 
are  derivable  from  a  single  mineral  or  that  they  are  unaltered  sediments. 
They  seem  to  be  in  this  region  the  most  stable  compound  which  could 
result  under  a  certain  set  of  physical  conditions  from  the  mutual  reaction 
of  siliceous  and  magnesian  substances. 

structural  evidence  as  to  origin. —  Serpentine  is  found  throughout  the  metamor- 
phic  areas  of  the  Coast  Ranges  in  very  irregular  patches,  both  near  quick- 
silver deposits  and  at  long  distances  from  the  mines.  In  some  metamorphic 
regions — for  example  in  the  immediate  neighborhood  of  Clear  Lake — it  is 
found  only  in  small  quantities,  while  at  Knoxville  and  at  New  Idria  large 
areas  are  almost  exclusively  composed  of  more  or  less  pure  serpentine. 

1  Origin  of  the  Crystalline  Rocks,  1884,  p.  53. 


MODE  OF  OCCURRENCE  OF  SERPENTINE.  121 

Near  the  Golden  Gate,  at  Mt.  Diablo,  and  in  many  other  localities  it  is  very 
abundant.  In  fact,  though  the  quantitative  relations  of  the  various  meta- 
morphic  rocks  vary  greatly  in  different  neighborhoods  along  the  quicksilver 
belt,  all  varieties  are  to  be  found  in  almost  every  district.  Serpentine  is 
commonly,  but  riot  always,  intimately  associated  with  pseudodiabase.  These 
rocks  stand  in  such  relations  to  the  unaltered  sandstones  in  very  numerous 
cases  that  no  geologist  carefully  examining  the  localities  could  fail  to  con- 
clude that  they  are  modifications  of  the  sandstone.  .  This  was  substantially 
the  conclusion  at  which  Professor  Whitney  arrived.  Knoxville  affords  ad- 
mirable opportunities  for  studying  this  connection.  Highly  inclined  strata 
strike  into  serpentine  areas  in  such  a  manner  as  wholly  to  preclude  the  sup- 
position that  the  serpentine  represents  an  earlier  mass  ;  one  side  of  an  an- 
ticlinal fold  is  serpentinizcd,  while  the  other  is  unaltered  and  carries  excellent 
fossils,  and  there  are  clear  cases  of  transition  through  altered  sandstones. 
Mt.  Diablo  affords  equally  favorable  opportunities  for  determining  the  age 
and  relations  of  the  serpentine.  In  many  other  localities  the  relations  of 
the  serpentine  to  unaltered  rocks  are  evident,  although  it  is  seldom  that  the 
age  of  these  unaltered  rocks  can  be  immediately  determined.  The  reason 
for  assigning  them  all  to  the  Neocomian  will  be  given  in  Chapter  V. 

Field  observation  makes  it  clear  that  in  most  cases  the  transformation 
to  serpentine  began  along  cracks  in  sandstone  or  in  rocks  resulting  from 
the  alteration  of  sandstone  and  worked  toward  the  centers  of  the  frag- 
ments thus  separated  from  one  another.  Where  this  process  is  incomplete, 
partially  rounded  nuclei  of  rock  retaining  the  sandstone  habitus  are  to  be 
seen,  divided  by  a  net-  work  of  serpentine.  Such  exposures  remind  one  of  the 
appearance  presented  under  the  microscope  by  olivines  in  process  of  con- 
version into  serpentine.  Sometimes,  but  not  often,  the  serpentine  assumes 
a  radial  form,  the  fibers  being  normal  to  the  surface  of  the  nucleus.  Pro- 
fessor Whitney  observed  such  an  instance  at  Newldria;  I  found  some 
very  beautiful  ones  at  Knoxville.  Two  cuts  illustrating  such  occurrences 
will  be  given  in  the  description  of  the  Knoxville  district. 

It  is  not  possible  from  a  mere  field  examination  to  determine  whether 
the  serpentine  results  directly  from  the  action  of  solutions  upon  sandstone  or 
whether  the  sedimentary  rock  first  becomes  crystalline  and  is  subsequently 


UNIVERSITY 


122  QUICKSILVER  DEPOSITS  OP  THE  PAOIFIC  SLOPE. 

serpentinized.  The  observer  would  incline  to  the  belief  that  both  methods 
were  followed,  but  the  conclusion  would  not  be  certain,  because  many 
rocks  which  are  really  holocrystalline  appear  to  the  eye  to  be  mere  sand- 
stones somewhat  modified.  It  will  be  seen  in  the  sequel  that  both  proc- 
esses can  be  traced  microscopically. 

The  serpentinoid  rocks  invariably  show  evidence  of  violent  dynamic 
action.  Traces  of  stratification  are  often  visible,  but  can  never  be  followed 
more  than  a  few  feet,  and  single  cropping?  frequently  exhibit  remnants  of 
stratification  in  all  sorts  of  contradictory  directions.  There  is  usually  little 
evidence  of  plication  ;  as  a  rule,  the  rock  was  reduced  to  a  confused  mass 
of  rubble  prior  to  serpentinization.  The  blocks  indeed  were  often  some 
yards  long,  but  even  these  were  generally  divided  by  numerous  cracks. 

Microscopical  evidence  of  derivation. Willie  it  is  not  possible  tO  follow  ill  tll6  field 

the  transitions  of  the  components  of  the  altered  rocks,  the  indications  of 
field  observation  were  found  to  be  borne  out  by  microscopical  and  chem- 
ical examination.  It  can  be  shown,  as  I  think  beyond  dispute,  that  all  of 
the  principal  minerals  of  sandstones  and  granular,  metamorphic  rocks  are 
converted  into  serpentine,  and  the  inference  with  regard  to  some  of  the 
less  important  Ones  is  also  strong.  After  the  investigations  of  the  last 
fifteen  years,  together  with  the  earlier  macroscopical  examinations,  it  will 
surprise  no  one  to  hear  that  in  the  granular,  metamorphic  rocks  of  the 
Coast  Ranges  augite  and  hornblende  are  found  passing  into  serpentine. 
The  attack  takes  place  along  the  surfaces  and  cracks,  exactly  as  in  uraliti- 
zation  and  chloritization,  while  the  resulting  mineral  has  all  the  distinctive 
characteristics  described  in  the  preceding  pages.  Sometimes  partial  pseu- 
domorphs  may  be  observed  in  which  a  kernel  of  the  bisilicate  is  embedded 
in  a  mass  of  serpentine,  surrounded  by  an  outline  characteristic  of  the  par- 
ent mineral.  This,  however,  is  rare,  apparently  because  well  developed 
crystals  of  augite  and  hornblende  are  also  rare. 

Though  Bischof,  vom  Rath,  and  others  have  shown  that  the  conver- 
sion of  feldspar  to  serpentine  was  probable,  I  am  not  aware  that  it  has  ever 
been  conclusively  proved.  In  the  altered  sandstones  and  the  granular 
metamorphics  of  the  Coast  Ranges,  however,  it  seems  beyond  doubt  that 
this  alteration  lias  taken  place.  In  very  numerous  cases  grains  of  feldspar 


PSEUDOMORPHIC  SERPENTINE.  123 

remain  embedded  in  serpentine,  and  these  grains  show  outlines  differing 
essentially  from  those  of  deformed  crystals  or  clastic  fragments,  but  resem- 
bling in  all  respects  corroded  masses.  Cracks  in  such  feldspars  are  also 
filled  with  serpentine,  and  it  is  manifest  "Tinder  the  microscope  that  feld- 
spathic  material  lias  been  removed  from  the  walls  of  these  cracks,  so  that 
they  woiild  no  longer  fit  were  they  brought  together.  This  evidence  is  of 
exactly  the  kind  commonly  accepted  as  proving  the  attack  of  other  min- 
erals. In  one  instance  the  phenomena  are  still  more  conclusive.  In  a  slide 
from  Sulphur  Bank  (specimen  No.  107),  a  feldspar  shows  such  a  crack  much 
widened,  and,  from  the  serpentine  mass  occupying  it,  sharp,  elongated  teeth 
of  serpentine  bite  into  the  clear  feldspar.  It  is  impossible  to  explain  such 
a  case  otherwise  than  as  an  actual  conversion  of  the  feldspathic  material 
under  the  action  of  corrosive  solvents.  The  serpentine  is  characteristic  and 
unmistakable.  The  feldspar  is  unstriated,  but  probably  triclinic.  Other  sat- 
isfactory occurrences  show  that  both  plagioclase  and  orthoclase  are  converted 
into  serpentine. 


FIG.  4.  Clastic  quartz  partially  converted  to  serpentine,  which  penetrates  from  the  ontsicle  in  needles.    The  specks  within 
the  quartz  are  fluid  in.-luaions  and  the  straight  prism  is  a  small  apatite.     Magnified  5,'i  diameters. 

That  quartz  is  sometimes  converted  into  talc  is  well  known  In  the 
altered  sandstones  of  the  Coast  Ranges  it  is  converted  into  serpentine. 
This  is  shown,  exactly  as  in  the  case  of  feldspar,  by  the  presence,  in  patches 
of  serpentine,  of  irregular  grains  of  quartz  with  corroded  surfaces  A 
very  beautiful  case  of  the  conversion  of  quartz  to  serpentine  occurs  in 
altered  sandstone  from  Clear  Lake  (specimen  No.  57),  and  is  illustrated 
in  Fig.  4.  A  clastic  quartz  grain  of  characteristic  form,  full  of  fluid  inclu- 
sions, containing  an  embedded  apatite  microlite,  and  behaving  as  usual  in 
polarized  light,  has  been  attacked  from  the  outside.  The  exterior  of  the 


124  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

original  mass  is  now  entirely  occupied  by  felted  fibers  of  serpentine,  and 
long,  slender  microlites  pierce  the  quartz  grain  toward  its  center  like  pins 
in  a  cushion.  That  there  might  be  no  doubt  as  to  the  correct  interpreta- 
tion of  this  important  case  another  quartz  was  selected  in  the  same  slide, 
which  showed  the  same  phenomena,  though  less  beautifully.  This  was 
tested  by  chemical  methods,  as  described  on  page  112,  and  the  green  min- 
eral was  proved  to  be  a  silicate  of  magnesium,  attackable  by  chlorhydric 
acid.  The  serpentine  which  was  chemically  tested  in  this  second  case  was 
absolutely  indistinguishable  in  color,  texture,  or  behavior  in  polarized  light 
from  that  surrounding  the  quartz  shown  in  the  figure,  and  the  distance  of 
the  two  occurrences  from  each  other  was  only  about  3nim.  The  long  mi- 
crolites which  pierce  the  quartz  are  of  the  same  color  as  the  strip  of  ser- 
pentine occupying  the  periphery  of  the  section.  Their  optical  properties 
capnot  be  well  observed,  because  they  are  embedded  in  the  brilliantly 
polarizing  quartz,  but  there  appears  no  reason  to  suppose  that  they  differ 
chemically  from  the  serpentine  at  their  bases.  Even  if  they  belonged  to 
another  mineral  species,  however,  the  structure  is  such  as  to  show  that  they 
must  be  regarded  as  an  intermediate  product  between  quartz  and  the  sur- 
rounding serpentine,  which  would  make  little  difference  from  a  geological 
point  of  view. 

Apatite  is  found  in  process  of  conversion  to  serpentine  in  specimen  No. 
107,  Sulphur  Bank,  one  of  the  specimens  in  which  the  presence  of  autlii- 
genetic  apatite  was  proved  by  chemical  as  well  as  by  optical  means.  The 
apatite  crystals  embedded  in  serpentine  in  this  slide  are  seen  to  be  cor- 
roded and  the  indentations  are  occupied  by  serpentine.  As  already  men- 
tioned, Professor  Dana  has  observed  pseudomorphs  of  serpentine  after 
apatite. 

There  are  also  a  number  of  cases  in  which  chlorite  appears  to  be 
altered  to  serpentine.  Thus  in  specimen  No.  261,  Sulphur  Bank,  a  chlorit~ 
ized  pseudodiabase,  areas  of  chlorite  are  intersected  by  cracks,  along  the 
walls  of  which  serpentine  is  disposed  in  such  a  way  as  to  lead  to  the  belief 
that  the  latter  mineral  is  epigenetic  ;  but,  as  in  the  case  of  the  conversion  to 
epidote,  the  fibrous  character  of  the  chlorite  somewhat  weakens  the  evi- 
dence obtainable  from  observation.  Bischof  regarded  the  serpentinization 


rSEUBOMORPHIC  SERPENTINE.  125 

of  chlorite  as  probable.1  Mica  and  garnet  have  been  observed  elswhere 
undergoing  conversion  to  serpentine..  The  mica  foils  are  so  small  and  pos- 
sess such  irregular  outlines  in  most  of  the  rocks  of  the  Coast  Ranges  where 
serpentinization  can  be  traced  that  this -change,  though  probable,  cannot 
be  definitely  asserted.  Garnet  is  seen  in  the  few  slides  which  show  it  in 
process  of  conversion  to  chlorite;  but  a  change  to  serpentine  has  not  been 
distinctly  traced  in  the  Coast  Ranges.  Zoisite,  as  it  occurs  in  these  rocks, 
is  not  well  suited  to  exhibit  pseudomorphic  alteration.  It  appears  in  smaller 
quantity  in  the  rocks  containing  much  serpentine,  however,  than  in  those 
containing  little.  The  prevalence  of  this  mineral  in  the  saussuritic  gabbros 
of  Europe,  the  intimate  relations  between  these  rocks  and  the  serpentines, 
and  the  absence  of  observations  on  the  presence  of  zoisite  in  massive  ser- 
pentines, either  in  the  Coast  Ranges  or  elsewhere,  point  towards  the  prob- 
ability of  a  serpentinization.  Olivine  has  not  once  been  detected  in  the 
rocks  associated  with  serpentine  in  the  Coast  Ranges  or  in  the  serpentines 
themselves,  and  olivine  cannot  have  contributed  in  an  appreciable  degree  to 
the  formation  of  these  serpentines,  important  as  is  the  part  which  this  min- 
eral plays  in  some  other  serpentinoid  areas. 

The  chemical  changes  indicated  by  the  observations  described  above 
on  the  alteration  of  bisilicates,  feldspar,  quartz,  and  apatite  to  serpentine 
are  very  strange,  and  the  results  may  possibly  fail  to  be  accepted  by  some 
because  of  their  strangeness.  It  is  a  truism,  however,  that  observation 
almost  always  outstrips  scientific  theories,  or  that  these  are  commonly 
framed  to  embrace-  the  results  of  observation,  while  the  changes  indicated 
here  are  not  more  perplexing  than  many  other  reactions  once  were,  for 
which  reasonable  explanations  have  been  discovered.  Mineral  chemistry  is 
full  of  puzzles,  some  of  them  so  familiar  that  their  chemical  difficulties  are 
hardly  appreciated.  That  a  number  of  different  minerals  should  all  be  re- 
placed by  serpentine  under  certain  appropriate  conditions  is  in  itself  not 
more  remarkable  than  that  from  a  single  solution  an  equal  number  of  min- 
erals should  be  precipitated  almost  or  quite  simultaneously;  yet  in  the 
study  of  veins  such  cases  occur  so  frequently  that  they  attract  no  attention. 

1  Lehrbuch  chem.  und  phys.  Geol.,  vol.  2,  1864,  p.  7*'.). 


126  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

It  has  doubtless  happened  in  times  past  that  observers  have  attempted  to 
cut  the  gordian  knot  of  metamorphism  by  assuming  such  replacements  as 
seemed  convenient.  This  method  of  dealing  with  the  subject  is  as  super- 
ficial as  a  flat  denial  of  all  conceivable  methods  of  genesis,  excepting  one,  of 
a  certain  product. 

General  course  of  serpentinization Having    Stated    in   detail    tll6    character  of   the 

evidence  as  to  the  serpentinization  of  the  mineral  constituents  of  the  sand- 
stones and  the  granular  metamorphic  rocks,  it  only  remains  to  indicate  the 
course  of  the  transformation  as  a  whole.  In  the  sandstones  which  have 
merely  weathered,  but  which  have  not  been  subjected  to  even  incipient 
recrystallization,  or,  in  other  words,  in  the  sandstones  of  later  age  than  the 
Neocomian,  serpentine  has  not  been  detected  with  certainty,  though  it  has 
been  carefully  sought,  while  chlorite  is  common.  I  know  of  no  reason, 
however,  why  small  quantities  of  serpentine  should  not  hereafter  be  found 
in  these  rocks.  There  is  abundant  evidence  that  serpentinization  was  not 
widespread  or  important  in  the  later  rocks,  but  this  does  not  exclude  local 
or  partial  repetition  at  later  dates  of  the  conditions  which  induced  serpen- 
tinization at  the  close  of  the  Neocomian. 

One  of  the  important  results  of  this  investigation  is  that  the  slightly 
recrystallized,  older  sandstones  were  subject  to  serpentinization  as  well 
as  those  which  had  undergone  complete  transformation.  In  these  rocks, 
of  course  the  more  permeable  aggregates  yielded  most  readily  to  attack 
and  were  first  affected  by  the  change.  In  such  cases  the  phenomena  of 
recrystallization  and  serpentinization  may  be  studied  side  by  side,  and  it 
is  rarely  the  case  that  some  small  patches  and  streaks  of  serpentine  are 
not  observable  in  these  sandstones.  At  a  further  stage  the  interstitial  space 
between  the  remains  of  the  clastic  grains  is  almost  wholly  filled  with  ser- 
pentine, which  then  attacks  these  nuclei,  as  has  been  described,  though,  as 
might  be  expected,  the  process  is  irregular,  so  that  one  portion  of  a  slide 
is  often  more  serpentinized  than  others.  The  quartz  appears  to  yield  more 
slowly  to  serpentinization  than  the  feldspar,  and  this  more  slowly  than  the 
fine-grained  cement.  The  extent  of  surface  exposed  is  of  course  an  im- 
portant factor.  As  the  amount  of  the  serpentine  increases,  traces  of  grate- 
structure  make  their  appearance;  but,  though  this  fact  is  easily  established, 


DECOMPOSED  SERPENTINE.  127 

the  material  at  hand  does  not  afford  the  means  of  following  in  detail  the 
history  of  the  grate  structure. 

In  the  pseudodiabase  and  pseudodiorite  it  is  naturally  the  bisilicates. 
which  first  show  traces  of  the  serpentimzation  process,  and  for  these  min- 
erals the  history  is  exactly  parallel  to  that  of  direct  chloritization.  The 
ferromagnesian  silicates  yield  to  this  process  much  more  easily  than  the 
feldspar  and  the  quartz,  which  behave  as  in  the  slightly  altered  sandstones. 
This  fact  leads  to  the  belief  that  the  greater  part  of  the  massive  serpentine 
has  resulted  from  pseudodiabase  and  pseudodiorite,  a  view  supported  by 
structural  considerations;  for,  since  both  recrystallization  and  serpentiniza- 
tion  are  dependent  on  a  fissure  system,  serpentinization  in  slightly  altered 
sandstones  appears  to  mean  that  during  this  process  the  solutions  diverged 
from  their  old  channels  or  that,  where  in  the  first  stage  solutions  permeated 
to  but  a  slight  extent,  they  penetrated  abundantly  at  the  later  period.  This 
would  probably  be  less  common  than  a  similar  distribution  of  solutions  at 
each  of  the  two  periods. 

Decomposition  of  serpentine. — In  nearly  all  the  serpentine  localities  it  is  evident 
that  this  rock  is  subject  to  tolerably  rapid  decomposition  under  the  action 
of  the  atmosphere.  The  subject  has  been  studied  in  Bohemia  by  Mr.  A. 
Schrauf,1  with  whose  results  the  observations  made  in  the  Coast  Ranges 

O 

agree.  Where  the  serpentine  is  directly  exposed  to  the  action  of  the  atmos- 
phere, it  is  often  bleached  and  converted  to  a  porous  mass,  which  is  nearly 
pure  silica,  containing  very  little  magnesia  or  iron.  Where  serpentine  has 
been  subjected  to  solfataric  action  in  the  immediate  neighborhood  of  ore 
bodies,  the  bases  have  often  been  removed  and  silica  has  replaced  nearly  or 
quite  all  of  the  original  mass.  While  this  is  a  common  change  near  ore 
bodies,  such  replacements  have  also  occurred  to  a  small  extent  at  long  dis- 
tances from  known  occurrences  of  ore,  and  it  may  be  that  this  process  has 
gone  on  to  some  extent  at  different  periods.  Since  by  far  the  greater  part 
of  the  silicified  serpentine  bears  such  a  relation  to  the  ore  bodies  as  to  lead 
to  the  conclusion  that  the  process  was  attendant  on  that  by  which  the  ore 
was  produced,  it  will  be  discussed  hereafter  in  that  connection. 

1  Zeitschr.  fiir  Krys.  und  Miu.,  Grotb,  vol.  6,  p.  321. 


128  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Serpentine  is  also  converted  into  carbonates  of  lime  and  magnesia  in 
the  Coast  Ranges,  and  the  process  can  be  followed  in  detail  in  some  cases. 
No.  223,  Knoxville,  is  a  grayish-green  serpentine  full  of  minute  veins,  the 
material  of  which  does  not  effervesce  with  cold,  dilute  chlorhydric  acid. 
Under  the  microscope  these  veins  are  seen  to  be  composed  of  carbonates 
often  exhibiting  cleavage.  On  removing  the  cover  it  was  found  that  a 
portion  of  the  carbonates  dissolved  slowly  in  cold  acid,  while  a  portion 
remained  unattacked.  Dolomite  and  magnesite  are  thus  probably  both 
present.  No  attempt  was  made  to  determine  the  quantity  of  magnesia 
in  these  carbonates. 

It  is  manifest  from  this  slide  that  the  substance  of  the  serpentine  lias 
actually  been  replaced,  for  the  masses  between  the  veins  are  rounded  and 
would  no  longer  fit  together  were  the  veins  removed.  The  result  is  a  net- 
structure  similar  to  that  observed  when  olivine  is  decomposed  to  serpentine. 

METAMORPHIC    ROCKS    OF    UNCERTAIN   AGE. 
Gavilan   Range  and  Steamboat  rocks. In  the  foregoing    pag6S   tllOSe  metaillOrpllic 

rocks  only  have  been  considered  which  are  actually  known  to  be  of  Knox- 
ville age  or  which  there  are  good  grounds  for  referring  to  that  epoch.  In 
the  course  of  this  investigation  metamorphic  rocks  of  uncertain  age  have 
been  encountered  at  two  localities.  One  of  these  is  in  the  Gavilan  Range, 
where  an  extraordinarily,  crystalline  limestone  is  associated  with  granite 
and  gneissoid  rocks.  The  occurrence  is  so  different  from  the  remainder  of 
the  altered  rocks  of  the  Coast  Ranges  examined  that  it  could  not  be  referred 
to  the  same  series  without  much  more  investigation  than  it  has  been  prac- 
ticable to  devote  to  it.  I  suspect  it  to  be  of  far  greater  age  than  the  rest 
of  the  exposures.  Under  the  microscope  the  gneissoid  rock  is  found  to  be 
of  the  Archaean  gneiss  type.  It  is  chiefly  composed  of  quartz,  orthoclasc, 
plagioclase,  and  biotite.  There  is  a  decided  tendency  to  granophyric 
structure,  and  veins  and  clusters  of  fibrolite  are  abundant.  This  rock  con- 
tains no  zoisite. 

At  Steamboat  Springs  the  sedimentary  rocks  are  greatly  disturbed  and 
in  part  highly  metamorphosed.  They  seem  to  belong  to  the  series  re- 
garded as  Jura- Trias  by  the  geologists  of  the  fortieth  parallel,  and  are 
certainly  older  than  the  Tertiary.  The  area  examined  is  too  small  to 


PKOOF  OF  METAMORPHISM. 

make  any  investigation  of  the  metamorphism  very  profitable.  The  sides 
show  that  a  portion  of  these  rocks  are  thoroughly  recrystallized  and  that  in 
mineral  composition  and  in  structure  they  strongly  resemble  the  metamor- 
phosed rocks  of  the  Knoxville  group  irrthe  Coast  Ranges.  There  is  at 
present  nothing  improbable  in  the  supposition  that  they  Avere  actually 
metamorphosed  at  the  same  time  The  study  of  these  rocks  will  be  re- 
sumed in  connection  with  the  geology  of  the  gold  belt  of  California. 

CONDITIONS    ATTENDING    THE   METAMORPHISM. 

In  the  foregoing  pages  the  unaltered  and  the  metamorphosed  rocks  of 
the  Coast  Ranges  have  been  described  from  a  lithological  point  of  view. 
It  remains  to  consider  the  metamorphic  process  as  a  whole  in  its  geological 
and  chemico-physical  relations. 

Proofs  of  metamorphism — The  division  of  opinion  as  to  the  origin  of  many  of 
the  crystalline  rocks  is  such  that  it  is  not  superfluous  to  insist  upon  the 
proofs  of  the  derivative  character  of  the  holocrystalline  rocks  and  of  the 
serpentine  of  the  Coast  Ranges.  It  appears  that  at  least  one  mineral  of 
nearly  universal  distribution  in  the  granular  and  schistose  rocks  and  in  the 
phthanites  is  especially  significant  in  this  respect,  and  that  a  sound  argu- 
ment may  be  based  upon  its  occurrence  independently  of  other  evidence. 

Zoisite  seems  to  be  characteristically  the  result  of  secondary  processes 
which  have  taken  place  at  no  very  high  temperature.  It  has  never  been 
observed  as  an  original  constituent  of  eruptive  rocks,  which  could  hardly  be 
the  case  if  it  were  at  all  common.  This  merely  negative  evidence  is  sup- 
ported by  that  afforded  by  its  composition,  which  includes  basic  hydrogen, 
while  no  such  compounds,  so  far  as  I  know,  have  ever  been  proved  to  form 
original  constituents  of  eruptive  masses,  and,  judging  from  what  is  known 
of  eruptions,  it  is  difficult  to  conceive  that  they  should  so  occur.1  On  the 

;  Zoisite  is  usually  referred  to  the  epidote  group,  of  which  only  ullauite  is  kuowii  to  occur  in  erupt- 
ive rocks.  The  composition  of  ullauite,  however,  is  somewhat  uncertain,  since,  according  to  Professor 
Rammelsberg,  it  has  the  oxygen  ratio  of  garnet  rather  than  of  ephlote,  while  there  appear  to  be  both 
hydrous  and  anhydrous  varieties.  According  to  Prof.  J.  D.  Dana,  the  hydrous  allanites  are  properly 
altered  forms  of  the  species.  There  can  be  little  doubt  that  the  unaltered  allauites  of  eruptive  rocks 
are  anhydrous. 

Messrs.  Fouque  and  Michel-Levy  regard  xoisite  as  a  scapolite,  for  which  I  know  of  no  ground  ex- 
cepting that  its  centesimal  composition  is  the  same  as  that  of  meionite.  The  scapolit.es  also  are  known 
only  as  the  result,  of  secondary  or  metamorphiu  action. 

3ION   XI II 9 


130  QUICKSILVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

other  hand,  zoisite  has  been  abundantly  proved  by  Hunt,  Cathrein,  and 
others  to  be  peculiarly  characteristic  of  rocks  which,  whether  regarded  as 
decomposed  eruptives,  as  metamorphic,  or  as  original  crystalline  sediments, 
indicate  the  formation  of  this  mineral  at  moderate  temperatures. 

Taking  all  these  circumstances  into  consideration,  it  appears  that 
scarcely  a  single  mineral  species  could  have  been  selected  which  would 
afford  a  better  criterion  of  the  prevalence,  at  the  epoch  of  its  formation, 
of  temperatures  decidedly  below  a  red  heat,  and  probably  much  below. 
Zoisite  might  conceivably  occur  in  two  ways,  and  it  is  not  improbable  that 
it  actually  does  so  occur.  If  found,  among  mere  decomposition-products, 
replacing  primary  minerals  pseudomorphically  as  aggregates,  it  would  seem 
to  prove  that  the  rock  in  which  it  occurred  had  simply  been  decomposed 
under  physical  conditions  appropriate  to  the  formation  of  zoisite  But,  if 
zoisite  is  found  embedded  in  clear,  continuous  masses  of  minerals  which 
can  be  shown  to  be  authigenetic,  it  would  seem  to  afford  conclusive  evi- 
dence that  these  minerals  have  been  formed  at  moderate  temperatures.  This 
latter  mode  is  characteristic  of  a  great  portion  of  the  rocks  of  the  Coast 
Ranges  and  very  often  in  cases  where  from  the  mere  inspection  of  slides 
it  might  readily  be  supposed  that  the  material  under  examination  was 
eruptive. 

While  zoisite  appears  to  form  an  admirable  indication  of  the  metamor- 
phic character  of  the  holocrystalline  rocks  of  California,  it  must  not  be  sup- 
posed that  their  determination  as  altered  sediments  is  dependent  on  the 
identification  of  zoisite.  Before  the  mineral  character  of  the  constituent 
which  proved  to  be  zoisite  was  known,  there  was  abundant  evidence,  both 
from  field  examination  and  from  microscopical  study,  that  the  rocks  in 
question  were  metamorphic,  and  the  conclusions  would  remain  substantially 
as  here  presented  if  it  should  be  proved  that  zoisite  is  a  common,  original 
constituent  of  the  most  typical  eruptive  diabases  and  diorites.  The  present 
investigation  may  properly  be  regarded  as  proving,  quite  independently  of 
its  chemical  constitution  or  of  its  occurrence  in  whatever  class  of  rocks  else- 
where, the  wide  distribution  in  metamorphic  rocks  of  zoisite  both  as  an 
authigenetic. constituent  and  as  one  of  the  first  of  these  constituents  in  the 
order  of  development. 


PKOOF  OF  METAMOEPHISM.  131 

The  stratigraphical  relations  of  the  holocrystalline  and  serpentinoid 
rocks  to  unaltered  beds,  in  part  fossiliferous,  at  a  great  number  of  localities 
are  such  as  absolutely  to  preclude  the  supposition  that  these  masses  are 
either  older  sedimentary  rocks  or  that  they  are  intrusive.  The  field  rela- 
tions of  the  holocrystalline  rocks  and  of  the  serpentine  to  the  sandstones, 
as  well  as  their  microscopical  character,  are  such  as  equally  to  preclude  the 
supposition  that  they  represent  local  or  regional  precipitations  of  crystalline 
sediments  of  the  same  age  as  the  fossiliferous  rocks. 

I  feel  almost  justified  in  stating  that  at  the  Post-Neocomian  epoch  of 
metarnorphism  the  rocks  of  the  Coast  Ranges  between  Clear  Lake  and  New 
Idria  contained  no  intrusive  masses  and  that  no  eruptions  accompanied  this 
upheaval.  It  is  true  that  in  a  few  cases  isolated  specimens  of  the  crystal- 
line, metamorphic  rocks  simulate  the  microscopic  appearance  of  eruptive 
masses  to  an  extraordinary  degree,  but  these  occurrences  when  examined  on 
the  spot  prove  to  pass  over  into  manifestly  metamorphic  material.  Two  or 
three  such  pseudoeruptive  rocks  were  discovered  in  the  collections  from  the 
Sulphur  Bank  and,  after  the  microscopical  work  recorded  in  this  chapter 
was  completed,  these  localities  were  revisited.  In  none  of  them  was  there 
the  slightest  structural  evidence  of  eruptivity ;  in  all  it  was  manifest  that 
the  suspected  rock  passed  over  into  ordinary,  unmistakably  metamorphic 
beds  within  a  few  feet  and  in  every  direction.  By  no  means  the  whole 
country  between  Clear  Lake  and  New  Idria  has  been  investigated,  but  so 
many  localities  have  been  examined  with  care  and  so  many  reconnaissances 
have  been  made  into  the  intervening  regions  that  it  would  be  very  strange 
if  any  considerable  quantity  of  eruptive  rock  occupying  the  position  indi- 
cated had  escaped  detection.  For,  though  a  particular  variety  of  lava  may 
sometimes  be  confined  to  very  narrow  limits,  as  is  the  case  with  the  rhyolite 
of  New  Almaden,  eruptive  phenomena,  once  initiated,  usually  and  perhaps 
invariably  extend  over  wide  areas 

Epoch  of  metamorphism — As  will  be  shown  in  a  subsequent  chapter,  the  age 
of  all  the  fossiliferous  rocks  associated  with  the  metamorphics  is  Neocomian 
Some  of  the  most  important  areas  of  metamorphic  rocks  are  certainly  of 
this  age,  and  reasons  will  appear  hereafter  for  supposing  that  no  consider- 
able portion  of  the  metamorphic  series  was  deposited  at  an  earlier  date. 


132  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  epoch  of  the  uplift  lies  between  the  end  of  the  period  in  which  the 
Knoxville  and  Mariposa  beds  were  deposited  and  the  beginning  of  that  in 
which  the  unmetamorphosed  Wallala  series  was  laid  down,  or,  according  to 
the  paleontological  determinations,  between  the  Neocomian  and  a  middle' 
Cretaceous  period  resembling  the  Gossau.  Unless  the  violent  dislocation 
which  took  place  between  these  periods  was  preceded  by  a  gentle  uplift  of 
the  country  above  water  —  and  of  this  no  evidence  is  known  —  the  folding 
and  crushing  which  form  so  prominent  a  feature  of  the  Coast  Ranges  must 
have  taken  place  at  the  close  of  the  Neocomian. 

That  the  metamorphism  cannot  have  preceded  the  uplift  is  certain, 
from  the  fact  that  the  confused  mass  of  rubble  resulting  from  dynamic 
action -has  often  been  recemented  by  the  metamorphic  processes.  The 
association  of  the  evidences  of  dynamic  action  with  the  alteration  is  such 
as  to  make  it  clear  that  the  metamorphism  was  to  a  great  extent  dependent 
on  the  crushing  of  the  rock.  There  is  no  evidence  that  any  considerable 
time  elapsed  between  the  crushing  and  the  ensuing  chemical  changes;  but, 
since  the  rocks  now  exposed  were  then  buried  at  a  considerable  depth,  such 
an  interval  might  have  elapsed  without  leaving  recognizable  traces.  On 
the  other  hand,  it  appears  certain  that  the  metamorphism  was  effected  under 
different  physical  conditions  from  those  now  prevalent,  because,  as  has  been 
pointed  out,  the  process  of  decomposition  now  progressing  is  inconsistent 
with  the  process  of  recrystallization.  It  is  most  natural  to  suppose  the  dif- 
ference to  have  been  one  of  temperature.  That  a  higher  temperature  pre- 
vailed in  the  rocks  at  the  time  of  the  upheaval  is  also  certain ;  for  the 
crushing  of  the  rocks  was  of  the  utmost  intensity  and  indicates  the  dissipa- 
tion, or  conversion  into  heat,  of  an  enormous  energy.  There  is  therefore 
strong  reason  to  suppose  that  the  metamorphism  followed  immediately  upon 
the  upheaval. 

Former  depth  of  the  present  exposures. —  In  comparing  the  metamorphic  Cretaceous 
rocks  of  the  Coast  Ranges  with  the  older  crystalline  schists,  particularly  as 
described  by  Dr.  Lehmann,  one  point  of  difference  is  especially  striking. 
In  the  older  rocks  fractures  are  comparatively  rare,  and  it  also  appears 
altogether  probable  that  at  a  sufficient  depth  below  the  surface  solids  must 
flow  rather  than  undergo  comminution.  Hence  the  intense  plication  of 


CONDITIONS  OF  METAMOKPHISM.  133 

such  rocks,  in  which  even  crystals  of  feldspar  are  bent  at  sharp  angles 
instead  of  breaking,  indicates  that  they  have  been  subjected  to  mechanical 
forces  of  great  intensity  while  under  immense  pressure  or  when  buried  at 
a  great  depth.  In  the  Coast  Ranges,  on-the  other  hand,  the  metamorphic 
rocks  have  been  crushed  to  an  astonishing  degree.  This  is  especially 
observable  in  the  phthanites,  which  are  often  intersected  by  so  fine  a  net- 
work of  minute  fissures,  now  filled  with  quartz  veins,  that  a  portion  of  the 
net  is  visible  only  under  the  microscope.  Plication  of  strata  is  indeed 
extremely  frequent ;  but,  at  least  in  a  great  proportion  of  cases,  this  has 
not  been  accomplished  to  any  great  extent  by  flexure  of  the  rock  mass.  It 
was  attended  by  the  formation  of  innumerable  cracks,  which  have  gaped 
more  or  less  and  thus  permitted  readjustment  without  great  displacement  of 
the  fragments.  The  fragments  having  been  recemented  in  their  new  posi- 
tion, the  strata  became  once  more  coherent.  Often  also  the  rocks  have 
been  crushed  to  a  mere,  confused  mass  of  rubble,  in  which  the  original 
stratigraphical  relations  are  entirely  obscured.  These  relations  appear  to 
demonstrate  not  only  the  expenditure  of  enormous  energy,  but  also  that 
the  Cretaceous  rocks  at  the  time  they  were  metamorphosed  were  not  buried 
at  great  depths,  perhaps  not  more  than  two  or  three  thousand  feet  below 
the  surface.  This  being  granted,  it  may  readily  be  understood  that,  even 
if  the  character  of  the  rocks  and  of  the  metamorphism  in  the  Archaean 
were  exactly  similar  to  that  of  the  Cretaceous  strata  of  the  Coast  Ranges, 
the  latter  would  inevitably  be  less  uniformly  altered,  while  at  least  the 
quantitative  relations  of  the  products  of  alteration  in  these  mountains 
would  probably  differ  from  those  characteristic  of  similar  masses  altered 
under  a  far  greater  and  far  more  uniform  pressure. 

Dynamic  conditions. — The  Post-Neocomiaii  uplift  was  accompanied  by  in- 
tense compression  in  a  northeast  and  southwest  direction.  The  strata  of 
the  Coast  Ranges  were  partly  plicated  and  partly  crushed,  while  on  the 
gold  belt  they  were  driven  into  a  nearly  vertical  position.  Both  areas 
appear  to  have  been  and  still  to  be  underlain  by  granite  at  no  very  great 
depth.  What  the  bed  rock  in  the  great  valley  of  California  may  be  is 
not  definitely  known,  but  there  seems  no  reason  to  suppose  that  it  is  not 
granite  there  also.  It  is  impossible  to  suppose  any  force  which  would 


134  QFJCKSILVER  DEPOSITS  OF  THE   PACIFIC  SLOPK. 

crumple  the  overlying  strata  by  horizontal  translation  over  the  granitic 
surface  while  the  granite  remained  undisturbed,  and  it  therefore  inevitably 
follows  that  the  granite  must  have  been  fissured  and  crushed  or  deformed, 
or,  more  probably,  crushed  in  the  higher  portions  and  plastically  molded 
in  the  deeper  regions.  The  granite,  like  the  sedimentary  rocks,  must  have 
been  heated  by  the  conversion  of  sensible  motion  into  molecular  motion. 

Nearly  all  rocks  are  permeable  by  water,  and  in  eveiy  region  there  is 
a  system  of  percolating,  subterranean  currents.  There  must  have  been 
such  systems  in  the  sedimentary  and  massive  rocks  of  California  before 
the  great  upheaval,  and  this  system  must  have  been  as  thoroughly  dis- 
turbed at  the  uplift  as  were  the  rocks  themselves.  Old  vents  were  closed, 
porous  beds  compressed,  and  the  fractures  caused  by  the  convulsion  cer- 
tainly afforded  new  paths  of  weak  resistance.  The  waters  were  warmed 
by  the  heated  rocks,  and  consequently  became  more  powerful  solvents, 
and  cannot  but  have  attacked  many  of  the  minerals  with  which  they  were 
in  contact. 

So  far  all  the  circumstances  appear  simple  and  certain,  and  it  may  be 
added  that,  since  the  uplift  as  a  whole  bears  the  character  of  a  violent  com- 
pression, the  interstitial  space  was  probably  greatly  diminished  and  the 
heated  mineralized  waters  were  driven  toward  the  surface  When  one  at- 
tempts to  pursue  the  subject  further  and  to  reason  upon  the  special  char- 
acter of  the  mineral  waters,  or  the  particular  temperature,  or  the  ensuing 
reactions,  observation  appears  to  be  the  only  guide.  A  priori  it  is  clear 
only  that  very  considerable  modifications  in  the  character  of  the  sedi- 
mentary rocks  must  be  expected  and  that  as  the  action  diminished  a  series 
of  transformations  might  occur.  So  far  as  can  be  known,  there  is  nothing 
unreasonable  in  the  supposition  either  that  the  solutions  may  have  been 
basic  at  some  points  and  acid  at  others  or  that  at  the  same  points  they 
may  have  been  basic  at  some  stages  of  metamorphism  and  acid  at  others. 

chemical  indications. — The  pseudodiabase  and  psendodiorite  are  much  more 
basic  than  the  sandstones,  as  is  also  the  serpentine,  while  the  phthanites 
are  more  acid  than  the  shales  from  which  they  are  derived.  Serpentin- 
ization  and  silicification  have  often  gone  on  in  the  same  rock  mass,  and 
the  evidence  from  many  widely  separated  localities  appears  to  indicate  that 


CHEMICAL  INDICATIONS.  135 

silicification  followed  serpentinization,  while  it  is  certain  that  serpentiniza- 
tion  postdated  the  formation  of  the  holocrystalline  metamorphics.  The 
serpentinoid  rocks,  like  the  phthanites,  are  sometimes  intersected  by  quartz 
veins,  but  the  conversion  of  serpentine  4nto  opal  has  taken  place  only 
locally  and  is  for  the  most  part  referable,  not  to  the  Fost-Neocomian  epoch 
of  metamorphism,  but  to  the  volcanic  period  of  ore  generation. 

A  difficulty  must  always  arise  in  discussing-  metamorphic  rocks,  from 
the  inevitable  lack  of  positive  knowledge  as  to  the  composition  of  the  sedi- 
ments prior  to  metamorphism.  It  is  indeed  one  of  the  advantages  which 
the  Coast  Ranges  afford  for  the  study  of  metamorphism  that  the  origin  of 
the  sediments  is  known  and  that  the  composition  of  the  unaltered  strata  as 
a  whole  is  uniform.  No  geologist  needs  to  be  told,  however,  that  this  uni- 
formity cannot  extend  to  hand  specimens.  It  is  impossible  to  say  that  any 
particular  sample  of  pseudodiabase  or  serpentine  once  had  the  composition 
of  a  second  sample  representing  unaltered  sandstone,  and  it  is  consequently 
also  impossible  to  ascertain  the  exact  quantity  and  quality  of  the  changes 
which  have  been  wrought  in  it  by  the  action  of  mineral  solutions.  It  fol- 
lows, however,  from  the  study  of  the  relations  of  many  metamorphosed 
masses  to  the  iinaltered  or  slightly  altered  rocks  surrounding  them,  that  the 
pseudodiabase,  pseudodiorite,  and  serpentine  are  as  a  whole  derived  from 
sandstones  of  average  character. 

The  fresh  sandstones  carry  magnesia,  but  not  in  great  quantities,  for 
the  allothigenetic,  ferromagnesian  silicates  form  a  small  part  of  the  mass, 
while  the  matrix  is  sometimes  nearly  pure  calcium  carbonate  and  never 
appears  to  contain  considerable  quantities  of  magnesia.  The  observations 
cannot  be  reconciled  without  supposing  that  very  large  quantities  of  mag- 
nesia have  been  supplied  in  solution  from  extraneous  sources,  though  the 
precise  quantity  cannot  be  determined  in  any  given  case.  One  and  only 
one  evident  source  for  this  supply  of  magnesia  exists,  viz,  the  ferromag- 
nesian silicates  of  the  underlying  granite.  The  wide  horizontal  extension 
of  the  granite  is  well  established.  Its  depth  is  entirely  unknown,  but  must 
be  very  great,  since  it  is  nowhere  cut  through.  An  inexhaustible  supply 
of  magnesia  was  thus  at  hand,  as  well  as  heated  waters,  with  a  probable 
upward  tendency  at  the  period  of  metamorphism,  but  under  what  precise 


136  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

conditions  magnesia  passed  into  solution  is  not  known,  nor  even  what  salt 
of  magnesia  was  dissolved.  The  structural  evidence,  however,  strongly 
favors  the  supposition  that  the  silica  of  the  sandstones  reacted  directly 
upon  magnesian  solutions.  Were  it  otherwise,  the  sandstones  might  have 
been  impregnated  with  hydrous  and  anhydrous,  ferromagnesian  silicates, 
but  the  quartz  grains  could  not  have  been  attacked,  as  they  certainly  are 
in  the  altered  sandstones,  while  in  the  recrystallized  rocks  they  have  alto- 
gether disappeared. 

The  experimental  researches  of  Dr.  Hunt  and  of  Mr.  Daubre'e  indi- 
cate the  kind  of  reaction  which  must  be  supposed  to  have  gone  on  in  the 
rocks  of  the  Coast  Ranges.  As  has  already  been  stated,  Dr.  Hunt  found 
that  when  alkaline  carbonates  in  solution  are  heated  with  silica  and  mag- 
nesium carbonate  an  alkaline  silicate  is  formed  which  reacts  upon  the 
magnesium  carbonate,  yielding  an  insoluble  magnesium  silicate  and  regen- 
erating the  alkaline  silicate.  So,  also,  Mr.  Daubre'e  discovered  that  water 
heated  at  a  high  pressure  in  glass  with  kaolin  results  in  the  formation  of 
zeolites,  feldspar,  pyroxene,  and  quartz.  In  such  experiments  the  tem- 
perature and  pressure  must  of  course  be  reduced  below  the  boiling  point 
before  any  satisfactory  examination  of  the  results  can  be  made.  Conse- 
quently, it  is  not  at  present  possible  to  say  under  what  special  conditions 
of  temperature  and  pressure  each  mineral  was  formed.  The  heated  waters 
in  the  granite  and  the  overlying  strata  of  the  Coast  Ranges  must  have 
contained  carbonic  acid  in  solution.  It  is  not  inconsistent  with  any  known 
facts  to  suppose  that  these  waters  attacked  the  granite  at  great  depths,  dis- 
solving alkalis,  magnesium,  and  iron,  with  perhaps  a  certain  amount  of 
silica;  nor  is  there  anything  to  forbid  the  supposition  that  at  lower  press- 
ures, and  perhaps  also  at  lower  temperatures,  such  solutions  brought  in 
contact  with  calcareous  sandstone  would  form  feldspars,  pyroxene,  amphi- 
bole,  and  serpentine.  In  the  experiments  solution  and  precipitation  were 
confined  to  the  same  locality,  while  in  the  Coast  Ranges  solution  went  on 
at  great  depths  and  precipitation  at  more  moderate  ones;  but  nothing  is  as 
yet  known  which  makes  it  necessary  to  suppose  that  the  conditions  of  tem- 
perature and  pressure  or  the  general  character  of  the*  reactions  in  the 
Coast  Ranges  differed  essentially  from  those  in  the  experimental  investiga- 


SIMCIFH1ATIOST.  1.37 

tions  referred  to.  It  would  b3  easy,  but  hardly  profitable,  to  speculate 
further  on  this  subject,  to  which  I  hope  to  contribute  by  experiment  on  a 
future  occasion. 

The  basic  solutions  rising  from  the  granite  converted  the  acid  sand- 
stones into  more  basic  compounds:  feldspars,  ferromagnesian  bisilicates, 
serpentine,  etc.  The  solutions  thus  became  more  acid,  and  it  can  hardly  be 
doubted  that  after  producing  their  full  effect  upon  the  sedimentary  rocks 
the  waters  contained  free  silica  in  solution.  It  is  an  interesting  and  impor- 
tant question  what  became  of  this  silica,  which  was  certainly  in  part  ex- 
tracted from  the  sandstones.  It  is  absolutely  certain  from  the  principle  of 
maximum  dissipativity  that  any  solution  will  deposit  its  contents  or  change 
its  chemical  character  at  the  very  first  opportunity  or  at  the  first  moment 
when  heat  can  be  set  free  by  any  chemical  or  physical  alteration.  Hence, 
in  general,  mineral  solutions  permeating  rock  masses  can  only  in  very  ex- 
treme cases  traverse  long  distances  without  substantial  change.  The  silica 
dissolved  by  the  waters  which  effected  the  metarnorphism  of  the  rocks  of 
the  Coast  Ranges  must  consequently  have  redeposited  this  material  as  near 
the  place  where  it  was  dissolved  as  possible.  There  appear  to  be  only  two 
possibilities  in  the  case:  either  the  silicification  which  is  so  prominent  in 
the  Coast  Ranges  was  due  to  these  siliceous  waters  or  the  solutions  pene- 
trated to  the  surface  of  the  region  as  it  then  existed  and  there  precipitated 
so  much  of  their  load  as  could  be  thrown  down  under  diminished  tempera- 
ture and  pressure.  My  own  preconceptions  would  incline  me  to  the  former 
of  these  hypotheses,  which  involves  a  speedy  precipitation  and  makes  a 
portion  of  the  process  of  metamorphism  independent  of  material  derived 
from  extraneous  sources.  This  may  bo  the  true  theory,  but  I  have  not 
been  able  to  gather  any  information  confirmatory  of  it.  Throughout  the 
field  work  efforts  have  been  made  to  determine  the  relative  age  of  the  proc- 
esses of  metamorphism,  and  in  each  area  it  has  appeared  that  silicification 
was  probably  a  later  phenomenon  than  serpentinization,  which,  again,  cer- 
tainly followed  the  recrystallization  of  the  sedimentary  rocks.  Thus  ser- 
pentinoid  rocks  are  often  intersected  by  quartz  veins,  while  such  veins 
partially  converted  into  serpentine  or  showing  infiltrated  serpentine  have 
nowhere  been  detected.  Massive  serpentines,  it  is  true,  are  seldom  pene- 


138  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

trated  by  quartz  veins  excepting  in  the  mines,  but  this  rock  is  too  soft  and 
tough  to  be  readily  fissured.  While  serpentinization  and  silicification  are 
usually  so  associated  as  to  lead  to  the  belief  that  the  latter  followed  the 
former,  it  is  anything  but  improbable  that  exposures  may  hereafter  be 
discovered  from  which  it  will  appear  that  at  least  in  some  cases  silica 
was  thrown  down  very  near  areas  of  serpentinization  and  simultaneously 
with  the  progress  of  the  latter  process. 

To  sum  up  the  results  in  a  few  words,  it  appears  reasonably  certain 
that  the  conversion  of  sandstones  and  shales  to  holocrystalline  rocks  took 
place  at  the  period  of  the  Post-Neocomian  upheaval  at  temperatures  some- 
what above  those  now  prevalent,  at  considerable  but  not  at  enormous 
pressure,  and  at  the  expense  of  basic  solutions  rising  from  the  underlying 
shattered  granite;  further,  that  serpentinization  of  holocrystalline,  metamor- 
phic  rocks  and  slightly  altered  sandstones  took  place  at  somewhat  lower 
temperatures,  also  at  the  expense  of  rising  solutions.  It  is  probable,  but 
not  absolutely  certain,  that  the  regional  silicification  was  subsequent  to  ser- 
pentinization and  mainly  produced  in  a  similar  manner.  The  formation  of 
ore  deposits  was  not  contemporaneous  with  the  metamorphism.  Impregna- 
tion of  the  rocks  with  calcite  and  gypsum  went  on  at  ordinary  temperatures 
and  is  still  in  progress.  Chloritization  was  effected  at  least  mainly  at  ordi- 
nary temperatures.  In  no.  case  which  has  been  examined  are  the  holo- 
crystalline rocks  of  the  metamorphic  series  injected  eruptives  or  original 
sediments,  nor  are  any  of  the  serpentines  studied  original  sediments.  No 
considerable  portion  of  the  serpentines  can  have  been  derived  from  olivine 
and  in  no  case  has  any  occurrence  of  serpentine  been  traced  to  an  olivinitic 
rock. 

Comparison  between   Neocomian  metamorphics   and   the  Archaean. \\  hetllCl"     tll6     Al'cllSBan 

rocks  are  metamorphosed  sediments  or  crystalline  precipitates  or  of  igneous 
origin  is  a  question  upon  which  eminent  authorities  differ,  and  one  upon 
which  neither  evidence  nor  argument  will  be  offered  here.  It  is  a  matter  of 
interest,  however,  to  compare  the  altered  strata  of  the  Knoxville  group  with 
the  crystalline  Pre-Paleozoic  rocks,  since  they  appear  to  have  much  in  com- 
mon. That  there  is  no  slight  similarity  between  the  metamorphic  rocks  of 
the  Coast  Ranges  and  the  strata  of  Archaean  areas  is  evident  from  the  fact 


COMPARISON   WITH  THE  ARCILEAN.  139 

that  more  than  one  well  known  geologist  has  believed  that  he  recognized 
as  Archaean,  areas  now  known  to  be  Neocomian.  The  metamorphism  of  the 
Coast  Ranges  may  fairly  be  considered,  at  least  in  part,  as  regional,  since 
most  of  the  rocks  of  the  Knoxville  group  are  considerably  altered  and  there 
are  areas  of  many  hundred  square  miles  now  exposed  in  which  no  patches 
of  unchanged  or  very  slightly  modified  rocks  are  known  to  exist.  Nothing 
like  the  uniformity  often  prevalent  in  Archaean  areas,  however,  is  to  bo 
found  in  the  Coast  Ranges.  On  the  other  hand,  though  the  general  appear- 
ance of  many  of  the  Knoxville  rocks  differs  widely  from  that  of  correspond- 
ing Archaean  masses,  there  is  much  similarity  in  detail.  Recrystallization  is 
very  prevalent  in  the  California  metamorphics  and  a  crystalline  development 
is  characteristic  of  the  Archrean.  Muscovite  rocks  are  frequent  in  the  Coast 
Ranges,  while  biotite,  though  rare,  is  certainly  one  of  the  authigenetic  min- 
erals in  the  California  metamorphic  area.  Plagioclase,  augite,  and  horn- 
blende are  also  abundantly  developed.  Mineral  combinations  similar  to 
those  of  diabase,  gabbro,  and  diorite  are  common  both  in  the  Coast  Ranges 
and  in  many  Archaean  areas.  Gneissoid  rocks  carrying  albite  and  orthoclase, 
though  not  predominant  in  the  Coast  Ranges,  are  found  there,  and  the  mixt- 
ure of  zoisite  and  plagioclase,  called  saussurite,  is  frequent  in  both  series,  as 
are  also  the  accessory  minerals  ilmenite,  titanite,  rutile,  apatite,  and  chromic 
iron  Finally,  serpentine  is  even  more  common  in  the  Coast  Ranges  than  in 
most  Archaean  areas.  Of  the  more  important  features  of  the  Arcluean  series 
none  appears  to  be  entirely  absent  among  the  metasomatically  recrystallized 
rocks  of  the  quicksilver  belt  which  have  thus  far  been  investigated,  but  the 
quantitative  relations  of  the  various  minerals  and  rocks  in  the  two  series  are 
widely  different.  A  slight  difference  in  the  chemical  composition  of  the  sed- 
iments of  the  Coast  Ranges,  or  of  the  solutions  by  the  help  of  which  their 
recrystallization  has  been  effected,  or  of  the  pressure  under  which  the  reac- 
tions took  place  would  have  considerably  changed  the  quantitative  relations 
of  the  minerals  formed.  A  greater  depth  from  the  surface  would  manifestly 
also  have  promoted  uniformity.  Whatever,  then,  is  the  real  origin  of  the 
Archaean  series,  it  appears  certain  that  rocks  indistinguishable  from  them 
might  have  been  produced  under  conditions  not  greatly  dissimilar  to  those 
which  prevailed  in  the  Coast  Ranges  at  the  close  of  the  Neocomian. 


CHAPTER  IV. 

THE  MASSIVE  ROCKS. 

General  character  of  the  massive  rocks. Tll6     litliology     of     tllG     Pacific     slope 

received  so  much  attention  of  late  years  that  it  is  unnecessary  and  would 
be  undesirable  to  treat  the  eruptive  rocks  of  this  area  as  if  they  were 
undescribed.  The  region  is  indeed  vast;  but  it  is  also  one  in  which  the 
character  of  the  rocks  is  remarkably  persistent.  In  the  following  pages, 
therefore,  only  the  more  peculiar  features  of  the  massive  rocks  encountered 
in  the  present  investigation  will  be  enlarged  upon.  These  are  granite, 
older  porphyries,  andesites  of  several  varieties,  rhyolite,  and  basalt. 

PRK-TEBTIARY    ERUPTIVES. 

Distribution  of  the  granite. —  As.  has  been  stated  in  the  preceding  chapter, 
granite  appears  to  underlie  the  sedimentary  rocks  of  the  Coast  Ranges  and 
of  the  Sierra  Nevada.  According  to  Professor  Whitney,  a  large  portion  of 
the  mountain  system  from  Fort  Tejon  southward  is  composed  of  granite. 
There  are  also  large  exposures  of  it  in  Shasta  and  Trinity  Counties.  In  the 
region  between  Clear  Lake  and  New  Idria  it  is  found  in  the  Gavilan  Range, 
occupies  considerable  areas  near  Monterey,  forms  the  Farallone  Islands, 
and  appears  at  Point  Reyes  and  other  localities  in  the  neighborhood.  Near 
the  town  of  Gnadala,  on  the  coast,  in  Mendocino  County,  large  masses  of 
conglomerate  are  formed  of  granite  bowlders  cemented  by  granitic  detritus. 
In  the  interior  of  the  Coast  Ranges  north  of  San  Francisco  it  has  not  been 
met  with  in  place  to  the  south  of  the  Trinity  Mountains,  but  probably 
occurs  in  some  of  the  chaparral-covered  hills,  since  a  very  large  part  of  the 
pebbles  in  Cache  Creek  are  granite. 

140 


GRANITE.  141 

The  arcose  character  of  the  sandstones  of  the  Coast  Ranges  has  been 
described.  In  the  Sierra  Nevada  granite  is  abundant,  even  in  the  foot-hills. 
The  higher  Sierra,  where  not  masked  by  lavas,  consists  chiefly  of  this  rock. 
From  the  main  Sierra  range  the  granite~extends  to  Steamboat  Springs  and 
Washoe  Lake.  Here  it  disappears  under  the  eruptive  rocks  of  the  Virginia 
Range,  but  reappears  on  the  eastern  side  of  this  range  near  the  southern 
end  of  the  Comstock  lode. 

The  lithological  character  of  the  granites  examined,  from  the  Washoe 
district  to  the  Farallone  Islands,  does  not  greatly  vary,  the  chief  difference 
being  in  the  proportion  of  hornblende  present.  Some  of  the  granite  from 
the  neighborhood  of  the  Comstock  carries  little  or  no  hornblende,  while  at 
Washoe  Lake  hornblende  is  particularly  abundant.  A  moderate  amount 
of  hornblende  occurs  in  the  granite  of  Steamboat  Springs  and  on  the  west- 
erly slope  of  the  main  Sierra.  The  Rocklin  granite,  from  the  western  base 
of  the  range,  is  also  hornblendic.  In  the  central  Coast  Ranges  hornblende 
is  not  abundant  in  the  granite,  only  a  portion  of  the  specimens  showing 
this  mineral  and  none  a  very  large  amount. 

At  the  Comstock  and  at  Steamboat  Springs,  as  well  as  on  the  eastern 
slope  of  the  Sierra,  the  granite  immediately  underlies  strata  at  least  as  old 
as  the  Mesozoie.  In  the  Coast  Ranges,  also,  Neocomian  beds  rest  upon  it. 
No  distinctly  intrusive  granite  of  Mesozoic  or  Tertiary  age  has  been  rec- 
ognized in  the  present  investigation.  That  such  exists,  as  asserted  by  Pro- 
fessor Whitney,  I  by  no  means  deny;  but  there  is  at  least  some  ground 
for  supposing  that  the  main  part  of  the  rock  is  Archrean. 

Granite  Of  steamboat  springs. — This  is  a  rather  coarse-grained,  gray  rock,  the 
grains  averaging  1.5'":"  to  2mm  in  diameter.  Plainly  visible  are  quartz,  feld- 
spar (in  part  triclinic),  dark-green  hornblende,  and  black  mica.  Under  the 
microscope  are  seen  quartz,  oligoclase,  orthoclase,  dark-bro\vn,  uniaxial 
biotite,  dirty-green  hornblende,  and  accessory  minerals.  These  last  are 
apatite,  titanite,  zircon,  magnetite,  chlorite,  epidote,  and  ferric  oxide.  The 
quartzes  are  in  large  part  composite  grains  and  of  course  contain  fluid  in- 
clusions. The  feldspars  show  in  many  cases  undulous  extinction  and  very 
often  also  zonal  structure.  The  crystals  of  primary  consolidation  are  bet- 
ter distinguished  from  those  of  secondary  consolidation  than  is  usual  in 


142  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

granites.  Of  these  the  first  are  long  prisms  of  oligoclase  (with  appropriate 
extinctions),  more  or  less  irregular  prisms  of  hornblende  (often  with  good 
hexagonal  cross-sections),  and  irregular  foils  of  biotite.  The  minerals  of 
secondary  consolidation  are  quartz  and  orthoclase,  with  perhaps  a  portion 
of  tli3  oligoclase.  This  division  is  only  approximate,  however,  for  grains 
of  quartz  are  embedded  in  well  developed  hornblende  prisms  of  first  con- 
solidation. 

The  plagioclase  in  some  of  these  specimens  is  much  more  striking 
under  the  microscope  than  the  orthoclase,  and  this  fact  might  lead  an  ob- 
server to  doubt  which  mineral  predominated.  In  cases  of  this  kind  there 
is  really  no  means  of  determining  by  microscopical  examination  the  rela- 
tive quantities  present,  for,  since  the  areas  of  the  grains  cut  by  the  slide 
vary  with  the  form  and  position  t)f  the  grains  as  well  as  with  their  cubic 
contents,  the  most  careful  study  of  the  areas  exposed,  or  even  of  the  areas 
of  each  grain,  will  lead  to  no  definite  result  unless  the  difference  in  quan- 
tity is  very  great.  To  test  the  matter  42  grams  of  such  a  specimen  were 
reduced  to  a  grain  of  0.5mm,  which,  in  consideration  of  the  coarseness  of  the 
rock,  was  considered  sufficiently  fine,  and  separated  by  the  Thoulet  method. 
The  separation  seemed  very  successful,  there  being  a  very  small  loss  from 
dust.  The  following  is  the  result: 

Per  cent. 

(1)  At  specific  gravity  2.77,  ferromagnesian  silicates.... 17 

(2)  At  specific  gravity  2.67,  impure  feldspar 5 

(3)  At  specific  gravity  2.64,  feldspar 12 

(4)  At  specific  gravity  2.62,  quartz 34 

(5)  At  specific  gravity  2. CO,  feldspar,  with  some  quartz 9 

(6)  At  specific  gravity  2.58,  feldspar 12 

(7)  At  specific  gravity  2.5G,  feldspar 5 

(8)  At  specific  gravity  2.54,  feldspar 6 

The  only  triclinic  feldspar  detected  under  the  microscope  was  oligo- 
clase, and  the  feldspar  heavier  than  quartz  was  undoubtedly  of  this  species. 
As  appears  from  the  table,  about  17  per  cent,  of  this  mineral  fell  before  the 
quartz.  At  first  sight  it  would  appear  that  orthoclase  predominated  greatly 
in  the  rock,  since  the  larger  part  of  the  feldspar  is  lighter  than  quartz.  It 
is  a  suspicious  circumstance,  however,  that  the  range  of  densities  is  so  great, 
and  mixtures  are  to  be  suspected.  Chemical  tests  of  (5),  (6),  (7),  and  (8) 


UFIVSRSIT7 


GRANITE.          X&'.JT"'   <V^/     l43 

showed  considerable  quantities  of  soda  in  all  excepting  the  last.  Quan- 
titative determinations  of  the  alkalio  in  (6)  were  then  made,  giving  3.08 
per  cent,  potash  and  5.54  per  cent.  soda.  This,  however,  does  not  settle 
the  matter,  since  it  is  well  known  that  orthoclases  sometimes  contain 
more  potash  than  soda.1  The  specific  gravities  of  these  minerals  also 
vary  greatly,  but  it  is  certain  that  many  specific-gravity  determinations 
have  been  made  with  impure  material.  No  less  an  authority  than  Professor 
Tschermak  gives  the  specific  gravity  of  orthoclase  as  2.558;  albite,  2  624; 
anorthite,  2.758.  These  figures,  on  Tschermak's  theory,  would  give  oligo- 
clase at  2.658.  If  the  specific  gravities  of  (5),  (6),  and  (7)  be  assumed  to 
be  each  0.01  higher  than  that  at  which  they  fell  and  if  the  mixture  of 
orthoclase  and  oligoclase,  which  would  give  these  specific  gravities,  be  com- 
puted at  Professor  Tschermak's  figures,  it  will  appear  that  the  granite  in 
question  must  have  contained  almost  exactly  equal  quantities  of  oligoclase 
and  orthoclase.  Taking  into  account  its  association  with  less  plagioclastic 
rocks,  its  habitus,  etc.,  there  can  be  no  doubt  that  it  is  to  be  classed  as  a 
granite,  and  not  as  a  plagioclase  rock. 

There  are  light-colored  bands  in  the  granite  at  Steamboat  Springs 
which  bear  the  appearance  of  dikes  of  granitic  rock.  Under  the  mi- 
croscope these  dike-like  masses  are  found  to  be  somewhat  decomposed 
granite-porphyry,  showing  rounded  grains  of  quartz,  orthoclase,  oligoclase, 
and  remains  of  ferromagnesian  silicates  in  a  microcrystalline  groundmass 
which  appears  to  consist  mainly  of  orthoclase  and  quartz.  The  larger 
quartzes  in  this  rock  show  abundant  fluid  inclusions.  These  dikes  were 
not  observed  to  penetrate  the  overlying  metamorphic  rocks,  and  are 
probably  older  than  the  latter,  if  not  substantially  of  the  same  age  as  the 
granite. 

The  granites  collected  from  the  eastern  ridges  of  the  Sierra  are  not 
distinguishable  from  those  of  Steamboat  Springs ;  but  a  granite  from 
Washoe  Lake  shows  exceptionally  well  developed,  long  hornblende-crystals 
embedded  in  a  very  white  quartz-feldspar  mass.  The  mica  is  less  promi- 
nent. 


1  Compare  Dana:  Syst.  of  Miu. ;  and  Kolh:  Allg.  uudchem.  Geol. 


144  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

• 

Granite  from  the  Coast   Ranges The  Specimens    tVoill   tllC    Gavilail    Range,    from 

the  Farallones,  from  Marin  County,  and  from  Horsetown,  Sliasta  County, 
do  not  differ  notably  from  those  of  Steamboat  Springs.  A  portion  of  the 
Monterey  granite  is  extremely  coarse.  Microcline  was  observed  in  slides 
from  two  of  the  localities  mentioned;  muscovite  occurs,  but  is  not  common ; 
and  hornblende  is  present  in  some  of  them,  but  not  in  large  quantities.  The 
crystals  of  primary  and  secondary  consolidation  are  less  marked  in  the 
Coast  Ranges  than  in  the  Nevada  granite,  and  in  a  granite  from  Olema, 
Marin  County,  there  is  some  granophyric  structure.  These  differences, 
slight  as  they  are,  are  probably  due  rather  to  the  accidents  of  collection 
than  to  any  persistent  difference  in  type. 

Older  porphyries  of  the  Coast   Ranges. No    Cl'Uptive    TOCks     antedating     tllO     PoSt- 

Miocene  upheaval  have  been  detected  in  place  during  the  present  investi- 
gation ;  but  in  the  conglomerates  of  the  Knoxville  series,  at  Knoxville,  and 
in  a  conglomerate  stratum  lying  just  above  the  base  of  the  Chico,  at  New 
Idria,  pebbles  of  porphyry  have  been  found.  In  appearance  these  sets  of 
pebbles  strongly  resemble  each  other,  and,  although  there  is  considerable 
variation  in  their  mineralogical  composition,  they  seem  at  present  fairly  ref- 
erable to  a  single  group.  They  are  all  quartzose  and  the  quartzes  contain 
fluid  inclusions,  often  in  abundance.  There  are  also  patches  in  the  quartzes 
which  resemble  devitrified  glass.  There  are  in  some  cases  remains  of  por- 
phyritic  hornblende-crystals,  mostly  decomposed.  A  large  portion  of  the 
porphyritic  feldspars  are  plagioclastic  and  appear  to  be  referable  to  oligo- 
clase  and  andesine.  Many  of  the  porphyritic  feldspars  are  unstriated,  but 
none  was  detected  showing  good  cleavages  and  certainly  referable  to  ortho- 
clase.  The  feldspar  of  the  groundmass  is  microcrystalline  and  cannot 
be  satisfactorily  determined  under  the  microscope.  The  quantity  of  the 
groundmass  is  usually  so  large  that  the  feldspar  which  it  contains  must 
determine  the  classification  of  the  rock.  A  partial  analysis  was  made  of 
one  of  the  Knoxville  specimens  (No.  76)  with  the  following  result: 

Tor  cent. 

.Silica,  SiO'  68.800 

Soila,  NaJO 10.021 

Potassa,  KX> 0.012 

This  is  evidently  a  plagioclase  rock  and   must  be  considered  a  por- 
phyritic diorite. 


PORPHYRIES.  145 

Had  the  porphyries  found  in  the  Chico  conglomerate  been  ejected  after 
the  Post-Neocomian  upheaval  they  would  almost  certainly  have  been  de- 
tected in  the  extensive  exposures  examined  at  and  to  the  south  of  Ne\v 
Idria.  The  porphyry  at  this  point  is  therefore  probably  of  nearly  the  same 
age  as  the  similar  rock  found  associated  in  the  Knoxville  conglomerates 
with  granite  pebbles  and  with  fossils  characteristic  of  the  Knoxville  series. 
The  eruption  of  this  porphyry  must  antedate  a  part  of  the  Knoxville  period, 
and  the  negative  evidence  is  that  it  preceded  the  entire  group  of  strata  in 
which  the  fragments  occur.  Like  the  porphyry  found  in  the  granite  at 
Steamboat  Springs  it  is  not  improbably  little  younger  than  the  granite. 

Diabase  from  steamboat  springs. — Among  the  greatly  disturbed,  partially  meta- 
morphosed,  highly  inclined,  sedimentary  rocks  of  Steamboat  Springs,  which 
are  overlain  by  andesites  and  basalts,  occur  some  conglomerates.  In  these 
were  found  dark  pebbles  of  a  crystalline  rock  strikingly  resembling  the 
material  which  forms  the  east  wall  of  the  Comstock  lode  in  Virginia  City. 
Under  the  microscope  these  pebbles  proved  to  be  plagioclase-pyroxene 
porphyries  with  a  crystalline  groundmass.  The  pyroxenes  are  entirely 
decomposed,  but  the  chlorite  and  other  decomposition  products  retain  the 
characteristic  forms  of  augite  or  hypersthene.  To  which  of  these  minerals 
the  original  substance  belonged  cannot  therefore  be  told.  This  rock  is 
microscopically  as  well  as  macroscopically  indistinguishable  from  the  por- 
phyritic  diabase  of  the  Comstock.  The  beds  in  which  the  pebbles  occur 
are  at  least  as  old  as  the  Mesozoic.1 

LAVAS. 

volcanic  rocks  of  steamboat  springs. — The  andesites  and  basalts  of  Steamboat 
Springs  form  a  most  interesting  series  both  in  themselves  and  because  they 
throw  some  additional  light  upon  the  important  occurrences  near  the  Com- 
stock lode,  which  is  only  six  miles  from  the  Springs  in  a  straight  line  and 

1 1  have  already  drawn  attention  to  the  rocks  of  Steamboat  Springs  iu  a  paper  entitled  "  Washoe 
rocks"  :  Bull.  California  Acad.  Sci.  No.  G,  1836,  p.  'Jll;  see,  also,  my  paper  On  the  texture  of  massive 
rocks:  Am.  Jour.  Sci.,  :id  series,  vol.  33, 1837, p.  50;  and  Bull.  U.  S.  Geol.  Survey  No.  17,  On  the  Develop- 
ment of  Crystallization  in  the  Igneous  Rocks  of  Washoe,  Nevada,  with  Notes  on  the  Geology  of  tho 
District,  by  Messrs.  Hague  and  Iddings. 

MON  XIII 10 


146  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

lies  on  the  opposite  flank  of  the  same  range.  A  portion  of  this  series  also 
possesses  a  close  analogy  to  some  of  the  andesites  of  the  Coast  Ranges. 
A  detailed  account  of  the  occurrence  of  these  rocks  will  be  given  in  the 
descriptive  geology  of  the  locality.  Here  it  is  sufficient  to  state  that  the 
latest  eruption  is  normal  basalt  and  the  earliest  a  normal,  dense  hornblende- 
andesite,  while  between  the  two  comes  a  series  of  pyroxenic  eruptions 
which  form  a  natural  group.  All  of  this  group  have  the  rough  fracture  and 
porous  texture  which  a  few  years  ago  would  have  led  to  its  being  called 
trachyte.1  The  exposures,  as  is  so  usual  in  the  Great  Basin,  are  admirable, 
a  large  proportion  of  the  entire  neighborhood  being  bare  rock. 

Andesites  of  steamboat  springs. — The  predominant  variety  of  the  older  horn- 
blende-andesite  of  Steamboat  Springs  is  a  grayish-blue,  dense,  fine-grained, 
thin-bedded  rock,  with  a  few  porphyritic  feldspars  of  small  size.  It  is 
entirely  similar  to  one  variety  of  the  earlier  hornblende-andesite  of  the 
Washoe  district.  Intermingled  with  this  rock  in  the  eastern  portion  of  the 
mass  are  patches  of  coarser-grained  and  more  porphyritic  modifications. 
The  relations  of  these  patches  to  the'  fine-grained  material  were  studied 
with  great  care,  and  no  evidence  was  found  that  they  were  separate  erup- 
tions ;  on  the  contrary,  it  was  clear  at  several  points  that  they  represented 
merely  local  modifications  of  structure.  These  coarser-grained  rocks  are  in- 
distinguishable from  the  prevalent  older  hornblende-andesite  of  the  Washoe 
district.  In  the  western  area  of  the  earlier  hornblende-andesite  the  fine- 
grained, fissile  rock  is  also  abundant,  but  here  it  is  associated  with  consid- 
erable, masses  of  wkat  is  plainly  glassy  rock.  Transitions  were  distinctly 
traced  here  also. 

Under  the  microscope  no  very  definite  lines  can  be  drawn  between 
these  older  rocks.  Thus,  No.  313  is  a  gray  rock  showing  many  porphyritic, 
black  hornblendes  Under  the  microscope  this  specimen  is  found  to  be 
composed  of  brownish-green  hornblendes  with  heavy,  black  borders  (many 

'Previous  to  my  examination  of  the  Comstock,  the  United  States  geologists  and  Professor  Zirkel 
regarded  the  later  hornblcnde-audesite  of  Washoe  and  many  similar  occurrences  elsewhere  as  trachyte. 
I  showed  that  the  Washoe  rock  contained  no  sanidine  and  stated  that,  from  a  cursory  examination  of 
the  trachyte  slides  of  the  fortieth  parallel  collection,  there  was  "  much  reason  to  believe  that  trachyte 
occurs  less  often  than  had  been  supposed  in  the  Ore  it  B:isin  area"  (Second  Ann.  Rept.  U.  S.  Geol.  Sur- 
vey, 1880-'31,  p.  :!()();  Geology  of  the,  Comstock  Lode,  Mon.  U.  S.  Geol.  Survey  No.  3,  p.  374).  A  year 
later  Messrs.  Hague  and  I  Idhigs  announced  that  tliero  were  no  trachytes  in  the  collections  01  the 
fortieth  parallel  from  th .-.  (ire.it  I5.isin  (Thir.l  Ann.  Rrpt.U.  S.  Geol.  Survey,  18rfl-'32,  p.  12). 


ANDESITES.  147 

of  which  have  entirely  replaced  the  amphibole),  a  very  little  pyroxene,  and 
a  moderate  number  of  porphyritic  plagioclases  embedded  in  a  fine-grained, 
holocrystalline  groundmass  of  magnetite  and  feldspar,  a  portion  of  the  latter 
being  granular  and  a  portion  microlitic.  In  No.  25a,  a  light-gray  rock  with 
small  porphyritic  hornblendes,  the  amphibole  is  entirely  replaced  by  black 
border,  the  porphyritic  feldspars  are  small  and  few  in  number,  and  the 
gronndmass  is  a  more  uniform,  fine-grained  material.  No  18  is  a  specimen 
of  the  prevalent  fine-grained  variety  and  presents  under  the  microscope  no 
considerable  difference  from  No.  25«,  excepting  that  the  hornblendes  are 
smaller.  The  glassy  variety  of  this  rock  shows  under  the  microscope  small 
brown  hornblendes  with  heavy  black  borders,  an  occasional  pyroxene,  a 
few  small  porphyritic  feldspars,  and  a  groundmass  consisting  of  feldspathic 
microlites  and  magnetite  embedded  in  a  glass  base.  Fluidal  structure  is 
common. 

The  younger  andesites  of  Steamboat  Springs  are  all  of  the  trachytic 
type,  gray  or  reddish  or  yellowish  rocks,  rough  and  soft.  Though  these 
rocks  stand  in  such  close  relations  that  I  shall  venture  to  propose  a  single 
name  to  embrace  them  all,  they  are  divisible  into  three  groups.  In  one 
large  area  the  rock  is  extremely  uniform  and  is  essentially  a  pyroxene- 
andesite  containing  abundant  augite  and  hypersthene.  'A  few  very  minute, 
black-bordered  hornblendes  are  usually  visible  under  the  micz-oscope,  but 
they  certainly  do  not  form  1  per  cent,  of  the  entire  quantity  of  bisilicates. 
This  rock  contains  no  mica.  Large  porphyritic  plagioclases,  which  appear 
to  be  andesine,  are  embedded  with  the  bisilicates  in  a  groundmass  of 
feldspar  microlites  and  magnetite.  A  second  pretty  well  defined  variety  is 
a  hornblendic  rock  in  general  appearance  similar  to  the  first  variety.  It 
always  contains  more  or  less  pyroxene.  It  also  often  contains  mica.  This 
last  mineral  seems  to  be  entirely  absent  in  some  croppings  and  even  over 
small  areas.  A  few  flakes  only  occur  in  other  masses,  while  in  others  still  it 
is  fairly  abundant,  and  in  one  area  brown  mica  with  a  variable  angle  be- 
tween the  optical  axes  forms  a  large  part  of  the  rock.  This  rock  appears  to 
be  substantially  identical  with  that  which  I  called  later  hornblende-andesite 
in  the  Washoe  district,  where  also  mica  is  present  in  variable  quantities 
and  is  sometimes  absent.  Messrs.  Hague  and  Iddings  prefer  to  rename 


148  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

this  rock  hornblende-mica-andesite,  a  term  which  would  be  misleading*  as 
applied  to  Steamboat  Springs,  where  later  hornblende -andesite  is  certainly 
appropriate,  since  five  well  defined  dikes  of  it  cut  the  earlier  hornblende- 
andesite.  A  portion  of  these  dikes  show  mica  ;  the  others,  none.  The 
greater  part  of  this  rock  is  holocrystalline,  but  some  croppings  contain  glass, 
sometimes  in  imperfect  spherolitic  forms.  In  two  cases  hornblendes  with 
concentric,  double,  black  borders  were  noticed. 

More  interesting  than  either  of  these  varieties  of  the  younger -ande- 
sites  is  the  third,  which,  for  lack  of  a  better  name,  I  will  call  provisionally 
transition  andesite.  This  variety  occurs  in  a  number  of  areas  shown  on  the 
western  portion  of  the  map,  some  of  which  are  small,  isolated,  and  excel- 
lently exposed.  They  are  as  trachyticin  texture  as  the  associated  varieties 
and  are  frequently  laminated,  the  sheets  being  half  an  inch  to  an  inch  in 
thickness  and  not  very  sharply  divided  from  one  another.  The  andesites 
of  Clear  Lake  show  the  same  structure.  The  transition  andesites  are  of 
exceedingly  variable  composition,  even  in  the  smaller  areas.  Some  speci- 
mens are  almost  purely  pyroxenic;  others,  at  a  distance  of  only  a  few  feet, 
carry  much  more  hornblende  than  pyroxene.  Sometimes  mica  is  present, 
but  oftener  absent,  though  it  has  been  found  in  all  of  the  principal  areas. 
In  one  area  olivine  also  has  been  detected  in  several  specimens.  One  of 
these  comes  from  a  portion  of  the  rock  which  appears  to  lie  beneath  the 
remainder  and  is  much  denser  than  usual,  but  other  olivinitic  specimens 
are  of  the  ordinary  trachytic  type. 

The  younger  andesites  are  comparatively  recent,  though  older  than 
the  basalt.  They  show  few  signs  of  erosion  and  cap  a  large  part  of  the  Vir- 
ginia Range  near  Steamboat  Springs.  They  also  form  the  Flufaker  Buttes, 
between  Steamboat  and  Reno,  where,  too,  micaceous  and  non-micaceous 
rocks  are  found  in  company.  The  younger  andesites  are  nearly  contem- 
poraneous. The  highly  micaceous,  later  hornblende-andesite  overlies  and 
appears  to  have  followed  the  less  micaceous  portion  of  the  same  variety. 
The  relative  ages  of  the  pyroxenic  and  hornblendic  varieties  are  not  abso- 
lutely certain.  On  the  map  will  be  found  a  dike  of  later  hornblende-andesite, 
which  should  cut  pyroxene-andesite  were  it  younger  than  the  latter.  It  is 
not  thus  shown,  but  it  is  not  impossible  that  it  may  do  so,  for  at  the  points 


ANDESITES.  149 

where  it  should  be  exposed  the  ground  is  so  covered  with  bowlders  of  the 
pyroxene-andesite,  which  have  rolled  down  from  the  adjoining  hill,  that 
the  croppings  may  have  been  concealed.  Repeated  and  careful  search  was 
made  for  them  in  vain.  The  transition-andesite,  though,  like  the  others, 
certainly  younger  than  the  earlier  hornblende-andesite,  does  not  stand  in 
structural  relation  to  the  other  varieties.  That  it  is  very  nearly  of  the 
same  age  seems  certain.  In  the  Washoe  district  the  micaceous  rocks  suc- 
ceeded the  pyroxene  rocks  of  Mt.  Kate,1  but  are  connected  with  them  by 
transitions.  On  the  other  hand,  Mr.  Lindgren  found  that  near  Bodie  pyrox- 
ene outflows  succeeded  micaceous  ones. 

It  would  be  a  very  easy  matter  so  to  arrange  the  slides  of  the  older 
and  younger  andesites  of  Steamboat  that  they  would  seem  to  form  a  con- 
tinuous series,  and  a  tolerable  argument  might  thus  be  offered  for  regarding 
the  rocks  as  substantiallv  one.  It  would  be  more  difficult  to  treat  the  hand 

</ 

specimens  in  this  way,  while  no  observer  could  examine  the  rocks  in  place 
at  Steamboat  without  perceiving  the  difference  in  age  and  geological  posi- 
tion of  the  older  and  younger  andesites 

The  services  which  the  microscope  renders  to  lithological  geology  are 
very  great,  but  there  are  facts  connected  with  this  study  which  are  not  best 
elucidated  by  examining  the  rocks  a  square  millimeter  at  a  time.  It  might, 
indeed,  be  said  that  since  these  rocks  are  so  closely  allied  it  is  useless  to 
make  geological  distinctions  between  them;  but,  if  the  purpose  of  lithology 
is  to  ascertain  the  causes  which  underlie  the  variations  in  composition  and 
structure  of  rocks,  the  progress  of  this  branch  of  science  could  only  be 
delayed  by  a  failure  to  study  and  record  all  the  distinctions  which  it  is  pos- 
sible to  trace.  When  these  causes  are  once  understood,  and  not  before,  it 
will  be  possible  to  judge  what  differences  are  truly  significant. 

A  natural  group  Of  andesites. —  A  fact  of  some  importance,  at  least  to  the  field 
geologist,  which  is  clearly  brought  out  by  the  study  of  the  rocks  of  Steam- 
boat Springs  and  confirmed  by  observations  in  California,  is  that  there  is  a 
group  of  comparatively  recent  andesites,  varying  considerably  in  mineral- 
ogical  composition,  but  possessing  much  macroscopical  similarity  and  a 
close  geological  relationship.  Most  of  the  younger  andesites  of  Steamboat 

1  Bull.  California  Acod.  Sri.  No.  (i,  vol.  '-'.  1. -Hi!.  \>.  01). 


150  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

would  unquestionably  have  been  classified  as  trachytes  by  nearly  every 
American  geologist  a  few  years  since.  They  are  nearly  all  soft,  rough, 
light-colored  rocks,  possessing  great  similarity  in  external  appearance  and 
in  their  mode  of  occurrence.  This  similarity  cannot  be  regarded  as  acci- 
dental, for  the  series  of  younger  andesites  found  at  Steamboat  is  repeated 
at  Mt.  Shasta,  which  I  visited  for  the  purpose  of  instituting  a  comparison, 
and  in  part  also  near  Clear  Lake,  while  the  area  regarded  as  trachyte  by 
all  field  observers  .  at  Washoe  previous  to  my  study  of  that  district  em- 
braces highly  pyroxenic,  non-micaceous  rocks  as  well  as  micaceous,  horn- 
blendic  andesite.  If  the  macroscopical  resemblance  and  the  intimate  asso- 
ciation of  these  rocks  be  not  accidental,  it  must  be  due  to  common  features 
in  their  origin  or  history,  and  they  may  therefore  properly  be  regarded  as 
forming  a  natural  group,  recognized  by  earlier  observers,  though  wrongly 
named.  They  are  all  more  or  less  pyroxenic  rocks,  which  may  contain 
both  mica  and  hornblende  or  one  of  these  minerals  or  neither.  Horn- 
blende occurs  in  this  series  over  large  areas  without  associated  mica,  and 
mica  (near  Clear  Lake)  in  large  areas  without  associated  hornblende.  The 
members  of  this  series  are  connected  by  transitions  wherever  I  have  studied 
them.  There  is  certainly  a  marked  distinction  between  this  series  and  the 
older  hornblende-andesite,  both  at  Steamboat  and  at  Washoe,  as  there  is 
also  at  the  latter  locality  between  it  and  the  earlier  dense  pyroxene-ande- 
site.  Near  Clear  Lake  also  the  earlier  pyroxene-andesite  is  distinct.  The 
causes  of  these  differences  are  not  as  yet  known.  I  do  not  believe  that 
they  depend  simply  upon  the  rate  of  cooling  or  upon  the  pressure  under 
which  the  rock  has  cooled.  As  has  been  mentioned,  a  portion  of  the  older 
hornblende-andesite  of  Steamboat  is  glassy,  while  directly  associated  with 
the  glass  is  ordinary,  dense,  older  andesite.  That  a  glassy  magma  cooled 
slowly  under  considerable  pressure  will  crystallize  appears  almost  certain, 
and  it  is  to  be  inferred  that  the  earlier  andesite  at  this  locality  has  not  been 
very  deeply  eroded.  Consequently  dense  andesites  may  consolidate  near 
the  surface.  On  the  other  hand,  there  are  many  exposures  of  the  younger 
andesites  at  depths  of  hundreds  of  feet,  and  in  the  Sutro  tunnel  at  a 
depth  of  some  2,000  feet  below  what  must  be  supposed  to  have  been  the 
surface  of  the  rock  at  the  period  of  eruption.  Such  exposures  are  indeed 


ASPE  RITES.  151 

holocrystalline,  but  tliey  retain  their  trachytic  character  in  spite  of  having 
cooled  at  great  depths.  I  incline  to  the  supposition  that,  owing  to  chemical 
differences  in  the  material  of  secondary  consolidation,  a  greater  change  of 
volume  has  accompanied  this  final  process-in  the  more  recent  series  than  in 
the  earlier  one  and  that  the  cracked  feldspars  and  the  smaller  cohesion  of 
the  trachyte-like  rock  are  due  to  this  change  of  volume.  Bulk  analyses  of 
the  younger  andesites  indicate  a  slightly  more  acid  composition,  but  it 
would  be  a  matter  of  great  difficulty  to  separate  the  crystals  of  primary 
and  secondary  consolidation  for  analysis.  Means  of  deciding  this  question 
may,  however,  be  devised. 

Should  the  series  of  younger  andesites  discussed  above,  together  with 
the  transitional  varieties,  prove  common  on  the  Pacific  slope  and,  as  a  rule, 
distinct  from  the  earlier  and  denser  rocks,  these  plagioclase  rocks  might 
conveniently  be  termed  asperitc*,1  at  least  for  field  purposes,  in  reference  to 
their  trachytic  character.  If  these  relations,  traced  by  me  at  four  impor- 
tant localities  and  suggested  by  hasty  inspection  at  other  points,  are  gen- 
eral, it  will  only  be  necessary  to  substitute  the  term  asperite  for  trachyte 
on  many  of  the  earlier  geological  maps  of  the  western  United  States  to 
represent  the  facts  from  a  modern  point  of  view.  Even  if  the  term  asperite 
does  not  obtain  a  permanent  place  in  lithological  nomenclature,  it  cannot 
be  amiss  to  consider  its  expediency.  The  nomenclature  of  lithology  is 
and  must  always  remain  more  or  less  arbitrary.  That  classification  is  the 
best  which  takes  account  of  the  greatest  number  of  natural  relations;  but 
no  classification  can  embrace  them  all.  To  my  mind  it  is  an  advantage 
that  the  term  asperite  expresses  structural  as  well  as  mineralogical  distinc- 
tions, for,  though  a  purely  mineralogical  classification  of  rocks  is  extremely 
simple,  it  ignores  many  of  their  properties  which  are  of  the  utmost  interest 
and  importance.  .  That  the  ultimate  classification  will  be  purely  mineralog- 
ical appears  to  me  in  the  highest  degree  improbable,  nor  can  I  believe  that 
it  will  be  founded  solely  upon  microscopical  peculiarities.2 

1  From  asper,  rough,  the  Latin  equivalent  of  T/iax_v~. 

'C.  W.  Giimbcl  (Sitzungsbcr.k.bayer.  Akad.  Wiss.,  Munich,  vol.  2,  1681,  pp.  305-36?)  suggested  ten- 
tatively that  the  audesitio  rocks  of  South  and  Central  America  might  be  divided  iuto  two  types,  one 
trachytic,  the  other  basaltic  iu  habitus.  I  was  not  aware  of  this  suggestion  when  the  text  was  writ- 
ten. Giimbel's  material  was  meager.  In  his  specimens  of  trachytic  habitus,  corresponding  to  my  as- 
periteg,  bo  found  no  mica.  The  specimen*  of  basaltic  habitus  which  ho  examined  iiirlu>lr<l  none  in 


152  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Andesites  of  the  quicksilver  belt. — Andesite  is  abundant  near  Clear  Lake,  and 
thence  southward.  This  region  was  studied  chiefly  for  its  bearing  upon 
the  geology  of  the  Sulphur  Bank,  and  no  attempt  was  made  to  investigate 
the  separate  varieties  of  andesite  minutely.  Besides  the  information  to  be 
derived  from  specimens,  however,  it  is  certain  that  the  andesite  of  this 
region  was  ejected  at  two  distinct  periods,  of  which  one  preceded  the 
Pliocene  Cache  Lake  beds.  This  earlier  andesite  is  largely  represented 
in  the  conglomerates  or  uncompacted,  pebbly  beds  of  Cache  Lake.  The 
later  andesitic  eruption  which  forms  the  mass  of  Mt.  Konocti  closed  the 
Cache  Lake  period  very  late  in  the  Pliocene,  but  preceded  the  basalt 
eruptions  by  an  unknown  though  considerable  interval.  The  older  ande- 
site, represented  by  Chalk  Mountain  and  by  the  pebbles  in  the  Cache 
Lake  beds,  is  a  rather  dense,  bluish-gray  rock,  somewhat  altered  in  most 
cases.  Under  the  microscope  it  is  found  to  be  composed  of  pyroxene  and 
feldspar  crystals  embedded  in  a  groundmass  consisting  of  feldspar  micro- 
lites  and  magnetite.  The  feldspar  of  the  groundmass  is  all  microlitic  and 
the  structure  is  similar  to  that  of  the  "felted"  groundmass  so  common  in 
pyroxene-andesites,  except  that  it  is  unusually  coarse.  The  pyroxene  is 
mostly  rhombic,  but  is  very  light  colored  and  shows  no  dichroism.  Pre- 
cisely similar  to  this  andesite  is  one  from  the  northern  end  of  Thurston 
Lake.  This  occurrence  appeared  from  field  examination  to  be  older  than 
the  asperites  by  which  it  is  accompanied,  while  from  its  similarity  under  the 
microscope  to  the  rock  of  Chalk  Mountain  it  seems  altogether  probable  that 
it  is  of  the  same  age  as  the  latter.  These  rocks  contain  no  hornblende. 

The  younger  andesites  of  Clear  Lake  are  referable  to  the  group  of 
asperites  discussed  above.  Macroscopically  they  are  dark-gray  or  tawny, 
soft,  trachytic  rocks,  often  showing  lamination  more  or  less  distinctly.  In 
fact  these  lavas  are  entirely  indistinguishable  from  some  of  the  andesites  of 
Steamboat  Springs.  They  are  pyroxene  rocks,  and  not  a  single  slide  shows 
a  particle  of  amphibole.  In  one  slide,  however,  are  a  few  minute  patches 
of  opacite  with  irregular  outlines,  which  possibly,  but  by  no  means  cer- 
tainly, replace  hornblendes.  On  the  other  hand,  mica  is  a  frequent  though 

which  hornblende  was  the  prevalent  bisilicate.  In  the  western  United  States  the  asperites  are  usually 
micaceous  and  dense  hornbleude-audesitcs  are  abundant.  The  latter  are  generally  distinct  from  the 
dense,  pyroxenic  rocks.  Gllmbcl  divides  his  types  at  57  per  cent,  of  silica. 


AXDESITIC  GLAS£.  153 

not  universal  constituent  of  these  rocks.  The  occurrence  of  biotlte  and 
pyroxene,  unaccompanied  by  a  trace  of  hornblende,  is  somewhat  excep- 
tional in  eruptive  rocks;  at  least  I  am  unacquainted  with  any  area  so  large 
as  that  at  Clear  Lake  which  is  thus  characterized.  In  other  respects  these 
andesites  are  not  peculiar,  showing  porphyritic  plagioclases  with  augite  and 
hypersthene  in  a  groundmass  of  feldspar  grains  and  magnetite,  sometimes 
holocrystalline  and  sometimes  accompanied  by  glass.  In  some  cases  where 
biotite  makes  its  appearance  the  pyroxene  is  found  to  be  exclusively  hyper- 
sthene, suggesting  that  the  mica  in  a  sense  replaces  or  represents  augite,  but 
augite  and  biotite  sometimes  appear  in  the  same  slide.  One  specimen  shows 
augite,  hypersthene,  biotite,  and  a  few  sharply  denned,  vividly  polarizing 
olivines.  The  groundmass  in  this  case  contains  some  base,  but  no  apprecia- 
ble amount  of  pyroxene,  and  there  is  nothing  basaltic  in  the  appearance  of 
either  the  specimen  or  the  slide.  The  porphyritic  feldspars  of  these  rocks, 
as  determined  by  optical  methods,  are  referable  to  labradorite  and  probably 
in  part  to  andesine,  while  the  microlitic  feldspars  show  the  extinctions  of 
oligoclase. 

At  two  localities  on  the  southerly  slope  of  Mt.  Konocti  dacite  is  found. 
One  of  these  is  about  half  way  up  the  slope,  the  other  near  the  foot.  It 
is  remarkable  that  cinnabar  is  associated  with  each  and  that  from  the 
higher  occurrence,  known  as  the  Uncle  Sam  mine,  considerable  quantities 
of  ore  have  been  taken.  The  rock  at  each  of  these  spots  is  much  decom- 
posed, but  what  remains  of  the  feldspar  is  all  triclinic  and  the  ferromag- 
nesian  silicates  were  certainly  principally  pyroxene.  No  distinct  evidence 
of  hornblende  or  mica  is  perceptible,  but  it  is  not  impossible  that  some  of 
each  exjsted. 

Andesmc  glass. —  Closely  associated  with  the  more  or  less  glassy  asperites 
of  Clear  Lake  are  large  areas  of  volcanic  glass.  This  glass  is  often 
opaque,  excepting  in  very  thin  splinters,  and  possesses  a  high  luster,  as  if 
charged  with  metallic  oxides.  Sparsely  distributed  in  it,  and  forming  cer- 
tainly less  than  1  per  cent,  of  the  mass,  are  sometimes  crystalline  grains. 
Such  a  specimen  is  No.  13,  Clear  Lake,  collected  half  a  mile  south  of  Kel- 
seyville.  Under  the  microscope  it  is  found  to  be  a  mass  of  light-brown 
glass,  full  of  excessively  minute,  black  trichites,  usually  arranged  in  stellar 


154 


QUICKSILVER  DEPOSITS  OE  THE  PACIFIC  SLOPE. 


groups.  A  few  small  grains,  but  no  lath-like  microlites,  of  plagioclase  and 
a  group  of  augite  and  hypersthene  crystals  also  appear.  The  microscope 
thus  confirms  the  reference  of  this  material  to  the  andesitic  eruptions.  This 
specimen  was  analyzed  with  the  result  given  below. 

For  comparison  with  this  glass  an  analysis  was  also  made  of  No.  7, 
Clear  Lake,  an  asperite  from  the  southeast  peak  of  Mt,  Konocti.  This  rock 
contains  a  few  quartz  grains,  but  is  otherwise  similar  to  most  of  the  asperites 
of  the  region.  It  is  sensibly  holocrystalline.  The  components  are  plagio- 
clase, augite,  hypersthene,  iron  ores,  and  quartz.  The  porphyritic  feld- 
spars are  probably  aridesine.  The  hypersthene  occurs  in  prisms  of  consid- 
erable length,  while  the  augite  is  found  in  small  grains.  The  groundmass 
is  chiefly  made  up  of  microlites  and  irregular  grains  of  plagioclase.  The 
rock  is  slightly  decomposed  and  contains  a  little  calcite. 

In  the  following  table,  I  is  the  andesitic  obsidian,  No.  13,  Clear  Lake, 
and  II  is  the  asperite,  No.  7,  Clear  Lake,  just  described: 


I. 

II. 

Specific  gravity  

2.391 

2  004 

Silica  «iO? 

74  013 

65  430 

Phosphoric  actd  psQ8                                               

0.010 

Titanic  acid  TiO2 

1,  04.1 

0  8°5 

Alumina  Al*03 

1°  049 

17  105 

Ferric  oxide  Fe2Os    

2  391 

1.415 

1  191 

Trace 

0  697 

Nickel  oxide,  NiO        .          .   .                              

0  'OJ 

0  905 

3  879 

Magnesia,  MgO  

0.480 

1  477 

Soda,Na'0  .             

5.340 

3  636 

Potassa.K'O  

4  019 

0  834 

Chlorine,  Cl  

0.074 

Loss  at  100°,  IL-O  

0.000 

0  °00 

Loss  above  100°,  H'O  

0  286 

0  361 

Total  (less  0-033  O)  

100  4"0 

100  248 

Atomic  ratio  of  I,  H-  :  Si  :  Rvi :  R"=0.032  :  4.934  :  0.7GO  :  0.36:3. 
Atomic  ratio  of  II,  H-  :  Si+Ti  :  Kvi :  R"=0.032  :  4.403  :  1.CD4  :  0.448. 

The  obsidian  is  much  more  acid  than  the  holocrystalline  rock  into 
which  it  passes  by  transitions,  but  this  is  not  the  only  chemical  difference. 
The  sum  of  the  quantities  of  lime  and  magnesia  is  less  than  one-third  as 
great  as  the  corresponding  sum  in  the  asperite,  while  the  glass  contains 


ANDESITKS.  155 

half  as  much  again  alkali  as  the  other  rock.  The  difference  in  the  specific 
gravities  is  also  noteworthy.  A  comparison  between  these  analyses  and 
those  of  some  basaltic  lavas  will  be  made  below. 

Andesites  south  of  cicar  Lake. — Extensive  amfts  of  aiidesite  occur  to  the  south- 
ward of  Clear  Lake.  Mt.  Cobb  and  Mt  St  Helena  and,  indeed,  a  great  part 
of  the  range  of  which  the  latter  forms  the  culminating  peak,  known  as  the 
Mayacmas  Mountains,  are  andesitic.  The  andesites  extend  down  almost 
continuously  to  within  a  few  miles  of  Vallejo,  at  the  head  of  the  Bay  of 
San  Francisco.  A  considerable  amount  of  reconnaissance  work  has  been 
done  in  this  area  for  the  purpose  of  studying  the  many  quicksilver  mines  or 
prospects  which  occur  in  the  same  region:  but  no  attempt  has  been  made 
to  map  this  andesite  area  or  to  work  out  the  separate  eruptions.  Both  dense 
andesites  of  the  earlier  type  and  the  asperites  are  represented.  All  the  speci- 
mens excepting  one  appear  to  be  purely  pyroxenic,  and  no  mica  has. been 
observed.  A  single  slide  from  near  Napa  City  shows  some  small  greenish- 
brown  "hornblendes,  accompanied  by  augite  and  hypersthene.  As  a  rule 
there  is  more  hypersthene  than  augite  in  these  rocks,  but  this  relation  is 
sometimes  reversed.  The  pyroxene  never  enters  in  considerable  quantities 
into  the  composition  of  the  groundmass.  The  feldspars,  both  porphyritic 
and  microlitic,  in  the  Mayacmas  Range  andesites  seem  to  be  mainly  labra- 
dorite,  a  fact  of  special  interest  in  view  of  the  abnormal  acidity  of  some  of 
them.  The  groundmass  of  most  of  the  slides  shows  feldspar  microlites  and 
magnetite  embedded  in  glass,  which  is  sometimes  partially  devitrified  and 
sometimes  full  of  trichites.  The  glass  often  shows  a  banded  or  rhyolitic 
structure. 

To  the  south  of  the  estuary  of  the  Sacramento  River  volcanic  rocks 
are  much  less  abundant  than  to  the  north,  but  they  are  not  entirely  want- 
ing. While  hornblende  is  unusually  rare  in  the  northern  andesites,  aspe- 
rite,  carrying  both  hornblende  and  mica,  occurs  near  Mt.  Diablo.  Professor 
Whitney1  mentions  a  belt  of  "trachyte"  some  fifteen  miles  northeast  of 
Tres  Pinos.  It  may  be  considered  certain  that  asperite  is  meant.  My 
party  has  not  visited  this  locality,  but  we  collected  pebbles  from  compar- 
atively recent  gravel  beds  and  from  the  present  streams  between  Tres 

1  Gcol.  Survey  California,  Geology,  vol.  1,  p.  4*. 


156  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Pinos  and  New  Idria,  many  of  which  are  entirely  similar  to  the  northern 
andesites.  That  these  rocks  must  be  in  place  somewhere  in  the  hills  is  of 
course  certain,  but  they  were  not  encountered. 

Rhyoiite. — Only  one  occurrence  of  rhyolite  is  known  in  the  whole  area 
dealt  with  in  this  memoir.  This  is  a  dike  at  New  Almaden,  far  from  any 
other  known  outcrop  of  eruptive  rock.  Its  occurrence  here  is  specially 
significant  when  considered  in  connection  with  the  ore  deposits.  The  crop- 
pings  are  mostly  of  a  tufa-like  consistency,  and  in  consequence  have  de- 
composed to  a  considerable  extent.  They  are  light  colored,  and  without 
careful  scrutiny  might  be  mistaken  for  clastic  material.  Under  the  micro- 
scope they  are  found  to  be  composed  of  porphyritic  grains  of  quartz  and 
feldspars,  both  striated  and  unstriated,  with  a  little  brown  mica  in  a  ground- 
mass,  which  is  sometimes  holocrystalline  (possibly  as  a  result  of  devitrifi- 
cation) and  sometimes  shows  the  pseudospherolitic  structure  so  common  in 
rhyolites.  In  the  latter  case  some  glass  remains  in  the  groundmass,  and 
inclusions  of  glass  are  common  in  the  quartzes  of  both  varieties.  To  de- 
termine the  character  of  the  predominant  feldspars  a  portion  of  specimen 
No.  47  was  reduced  to  coarse  powder  as  usual  and  separated  in  a  Thoulet 
solution  of  a  specific  gravity  of  2.59.  Eighty-one  per  cent,  floated.  This 
consisted  of  feldspar  with  groundmass  and  a  little  adhering  quartz  It 
gave  a  strong  potash  reaction.  This  rhyolite  is  later  than  the  Post-Miocene 
upheaval. 

Basalt.  —  Basalt  is  very  widely  distributed  on  the  Pacific  slope.  Being 
the  last  eruption,  it  is  seldom  covered  over  by  material  of  any  kind.  The 
thin  flows  of  this  rock  have  also  spread  over  a  greater  area  than  the  com- 
paratively viscous  andesites  of  equal  volume  could  have  done.  Both 
macroscopically  and  microscopically  the  rock  is  very  monotonous  in  its 
character  and  presents  comparatively  few  points  of  interest. 

At  Steamboat  Springs  the  thin  flows  of  olivinitic  basalt  are  found 
under  the  microscope  to  be  entirely  normal  and  precisely  similar  to  the 
basalt  of  the  Washoe  district.  Similar  rocks  are  found  in  the  Panoche  Val- 
ley, in  the  San  Benito  Valley,  near  Mt.  Diablo,  and  at  many  points  between 
the  Bay  of  San  Francisco  and  Clear  Lake.  Near  Clear  Lake  they  are 
somewhat  more  notable,  since  much  of  the  rock  at  this  point  is  scoriaceous 


BASALTS.  157 

and  forms  pretty  well  developed  volcanic  cones  of  small  size.  The  scori- 
aceous  basalt  does  not  differ  from  the  ordinary  variety  under  the  microscope, 
except  by  the  presence  of  many  cavities  and  a  comparatively  large  amount 
of  ferruginous  decomposition-products.  ~  In  this  region  olivine  is  very  ir- 
regularly distributed,  some  croppings  showing  unusually  great  quantities 
of  this  mineral,  while  in  others  it  is  macroscopically  and  microscopically 
absent.  This  irregularity  was  noticed  even  in  single  patches  of  the  rock, 
which  could  not  possibly  be  assigned  to  different  eruptions.  Whether 
olivine  is  absent  or  present,  the  structure  of  the  rock  remains  the  same,  the 
interstices  between  small,  lath-like  plagioclases  being  filled  with  pyroxene 
microlites.  Olivine.is  thus  a  frequent  but  not  an  essential  constituent  of 
the  California  basalts,  and  the  microscopic  distinction  between  this  rock 
and  andesite  consists  in  the  order  of  genetic  succession  of  the  component 
minerals.  The  olivine  frequently,  includes  quadrilateral  picotite  crystals 
and  as  a  rule  shows  signs  of  incipient  decomposition. 

The  feldspars  of  the  basalts  of  the  quicksilver  belt  are  seldom  porphy- 
ritic  and  they  usually  assume  the  form  of  elongated,  more  or  less  microlitic 
crystals,  often  with  terminal  faces.  The  predominant  species  is  labradorite, 
but  oligoclase  may  be  present  among  the  smaller  individuals.  The  pre- 
dominant pyroxene  is  augite,  which  is  sometimes  present  in  large  grains, 
but  always  as  small  grains  in  the  groundmass.  It  presents  no  peculiarities. 
Hypersthene  is  also  found  in  a  few  sections.  It  of  course  extinguishes 
light  when  the  principal  nicol  sections  are  parallel  to  the  main  axis,  and  it 
shows  interference  colors  which  are  gray  and  yellow,  differing  markedly 
from  those  of  augite.  Like  the  hypersthene  of  the  Chalk  Mountain  ande- 
site, however,  its  dichroism  is  not  sensible.  So  far  as  ascertained,  only  the 
larger  pyroxene  crystals  are  ever  hypersthene,  that  of  the  groundmass 
where  determinable  being  augite.  Hypersthene  has  been  supposed  by 
Messrs.  Hague  and  Iddings  to  replace  olivine.  To  some  extent  this  appears 
to  be  the  case  in  the  basalts  of  the  quicksilver  belt;  at  least  there  are  a 
number  of  thin  sections  in  which  hypersthene  occurs  and  which  do  not 
contain  olivine.  Olivine  and  hypersthene  also  occur  in  the  same  sections, 
however,  and  there  are  many  slides  in  which  neither  olivine  nor  hypersthene 
appears. 


158  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

At  Sulphur  Bank  the  basalt  bears  peculiar  and  very  interesting  rela- 
tions to  volcanic  glasses.  Field  examinations  showed  that  an  area  of 
obsidian  south  of  Borax  Lake  passed  over  into  a  rock  which  bore  every 
appearance  of  being  an  ordinary  basalt.  This  glass  is  a  dark-gray  ma- 
terial, transparent  in  masses  a  quarter  of  an  inch  or  more  in  thickness  and 
without  any  peculiarly  high  luster.  It  occurs  some  miles  from  any  ande- 
site  area  and  presents  a  very  different  appearance  from  the  andesitic  glass 
described  above.  On  analysis,  however,  it  proved  to  contain  above  75  per 
cent,  of  silica.  This  seemed  at  first  to  preclude  its  reference  to  a  basaltic 
eruption.  It  was  afterwards  found  that  No.  48&,  a  fine-grained  basalt  from 
one  of  the  craters  at  Sulphur  Bank,  normal  in  structure,  but  without  oli- 
vine,  of  a  specific  gravity  of  2.82,  contained  57.03  per  cent  of  silica,  a  very 
high  content  for  a  basalt;  while  No.  202,  occurring  at  the  outskirts  of  the 
obsidian  area,  is  a  somewhat  glassy  basalt,  density  2.69,  carrying  olivine, 
augite,  and  hypersthene,  with  feldspar  microlites,  and  showing  the  charac- 
teristic structure  of  this  rock,  contains  no  less  than  G6.87  per  cent,  of  silica. 
Even  No.  150J,  which  is  microscopically  a  pure  glass,  with  a  specific  grav- 
ity of  only  2.33,  and  which  carries  75.22  per  cent,  silica,  proves  under  the 
microscope  to  contain  numerous  small  grains  of  pyroxene  and  long  micro- 
lites of  plagioclase  entirely  similar  to  those  in  the  basalts.  Neither  free  quartz 
nor  orthoclastic  feldspar  has  been  detected  in  the  slides  of  this  obsidian. 
The  abundance  of  lath-like  plagioclases  in  this  glass  distinguishes  it  micro- 
scopically from  the  andesitic  obsidian,  in  which  the  feldspars  are  mostly,  if 
not  wholly,  irregular  grains  or  developed  crystals  of  primary  consolidation. 

The  microscope  thus  supports  the  conclusion,  reached  from  field  ob- 
servation before  either  microscopical  examinations  or  chemical  determina- 
tions had  been  made,  that  the  obsidian  near  Borax  Lake  is  a  portion  of  a 
basaltic  eruption.  The  transition  has  been  again  tested  in  the  field  since 
the  laboratory  work  was  completed. 

In  the  following  table  the  analysis  of  the  obsidian  from  the  area  imme- 
diately south  of  Borax  Lake  is  given  under  I.  For  comparison  a  second 
basalt  (No.  85,  Clear  Lake)  was  analyzed,  and  its  composition  is  given 
under  II.  This  latter  is  from  the  basalt  bluffs  south  of  Burns  Valley,  at 
no  great  distance  from  the  obsidian.  It  is  a  dense,  gray  rock,  remarkably 


BASALTIC  GLASS. 


159 


rich  in  olivine.  Under  the  microscope  the  rock  appears  wholly  normal, 
showing  the  usual  miorolitic  grouudmaas  of  plagioclase  needles  and  small 
augite  grains,  while  the  porphvritic  divines"  are  undecomposed.  The 
analysis  shows,  however,  that  it  is  rather  siliceous  for  a  basalt,  in  spite 
of  the  great  quantity  of  olivine.  Under  III  is  given  the  composition  of  an 
ordinary  basalt  from  Knoxville. 


I. 

II. 

III. 

2  390 

2  830 

Silica  SiO- 

75  40J 

57  374 

51   6G 

0  010 

Titanic  acid   TiO2             

0  CO0 

Trace 

Chromic  oxide   Cr'20!  

0  25 

Alumina  Al'O1 

7  722 

15  C04 

li  ->2 

Ferric  oxide   Fe"0* 

1  410 

0  064 

4  45G 

'7.02 

0  110 

0  °71 

0  12 

Nickel  oxidn,  NiO  

0  411 

1  551 

4  Oil 

7  72 

1  ^60 

8  838 

13  61 

Soda  "NTa?O 

8  090 

3  047 

5  98 

Potassa    K-O 

4  515 

1  507 

0  89 

Chlorine  Cl       ..               

0  1'9 

Loss  at  100°  Il'O 

f  0  614 

Loss  above  100°   H2O 

J      0.  428 

(  0  1°3 

J       1.06 

Total  (less  0.027  O  —0.110  Cl.  in  I)    

JOO.  085 

99  9"8 

100  13 

1  A  small  amount  of  iron  in  the  ferric  state  was  not  di'termineil,  because  unnecessary  for  the  purpose  for  which   the 
analysis  was  originally  made. 

Atomic  ratio  of  I,  H-  :  Si  :  R"  :  R"=0.  047  :  5.  027  :  0.  506  :  0.  474. 
Atomic  ratio  of  II,  H-  :  Si  :  fi'1  :  R"=0.  082  :  3.  825  :  0.  937  :  0.  887. 
Atomic  ratio  of  III,  H-  :  Si  :  fi"  :  U"=H.  118  :  3.  444  :  0.  669  :  1.  376. 

The  difference  in  composition  between  the  glass  and  the  nearly  holo- 
crystalline  basalts  is  extremely  similar  to  that  pointed  out  between  the  crys- 
talline and  glassy  forms  of  andesite.  There  is  nearly  three  times  as  much 
alkali  in  the  glass  as  in  the  olivinitic  basalt  from  Burns  Valley,  and  only 
one-fifth  as  much  lime  and  magnesia. 

It  is  a  curious  fact  that  if  10  per  cent,  of  lime  were  added  to  this 
obsidian  it  would  closely  approximate  in  composition  to  some  kinds  of 
window-glass. 

Analogous  occurrences. — The  association  of  coiiiparati velv  acid  glasses  with 
neutral  or  basic  lavas  is  not  unknown.  In  the  trachyte  of  Mt.  Amiata,  in 
Tuscany,  Professor  vom  Rath  found  small  grains  of  a  substance  which  had 


•£ 


foiriVSRSITY 


160 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


been  taken  for  quartz,  but  which  on  separation  and  analysis  proved  to  be 
glass.1  The  inclosing  rock  contained  67.06  per  cent,  of  silica,  while  the  fol- 
lowing analysis  shows  the  composition  of  the  glass : 

Specific  grav  ity 2.  351-2.  :><VJ 

Silica,  SiO2 76.82~~ 

Alumina.  A12O3 14.01 

Lime,  CaO 1.7C 

Water,  H-O 0.40 

Alkalis  (by  difference) 7.01 

100.  00 

In  this  case,  therefore,  the  amorphous  material  accompanying  well  crystal- 
lized components  contained  nearly  10  per  cent,  more  silica,  a  large  quantity 
of  alkalis,  and  very  little  lime.2 

In  the  basalt  of  the  Rossberg,  near  Darmstadt,  also,  Mr.  T.  Petersen3 
found  a  bottle-green  glass  inclusion,  or  segregation,  which  differed  very 
greatly  indeed  in  its  chemical  composition  from  the  surrounding  mass,  as 
is  shown  by  the  following  analyses: 


Rock. 

Glass. 

• 

3.043 

40.53 
1.80 
14.89 
1.02 
11.07 
0.10 
8.02 
U.flL' 
2.87 
1.95 
1.32 

2.524 

66.12" 
0.31 
13.07 

j'        3  66 

Trace 
1.80 

1.19 
6.09 
7.36 

Silica  SIO-                             

Tit'inir  arid  TiO7                   

Alumina  A1O1                                                 -•               

Magnesia,  MgO  

Lime  CaO                                         -  

Soda  Xa'-'O               

Potassa  K*O                         

Phosphoric  acid  P2O5                                

0.17 

Water  H2O                                    

1.44 

0.73 

99.  SO 

100.  13 

1  Zeitschr.  Dentsch.  geol.  Gesell.,  vol.  17,  1805,  p.  413. 

'2Al>out  the  time  at  which  this  monograph  was  transmitted,  a  very  elaborate  study  of  the  Amiata 
rocks  was  published  by  Mr.  J.  Francis  Williams  in  the  Xeues  Jahrbuch  fiir  Mineral.,  V.  Beilage-Band,  1887, 
p.  381.  He  regards  the  whole  mountain  as  a  single  massive  which  is  typically  developed  as  trachyte 
toward  the  center,  but  tends  sometimes  to  an  andesitic  and  sometimes  to  a  rhyolitic  composition  at  the 
edge.  The  rock  is  all  more  or  less  glassy.  A  very  pure  glass  from  Fosso  del  Diluvio  gave:  Sp.gr., 
2.346;  SiO2,  73.57;  CaO,  0.99;  MgO,  0.26;  Na2O,3.0l>;  K-O,  5.74.  An  analysisof  typical  trachyte  from 
the  Poggio  Traburzolo  gave:  Sp.  gr.,  2.562 ;  SiO2,  64.76;  CaO,  3.24;  MgO,  1.74;  Na-O,  2.67;  K-O,  5.49. 
As  in  the  case  of  the  Clear  Lake  andesite  and  basalt,  the  glass  is  more  acid  than  the  rock,  and  the 
proportion  which  the  alkalis  bear  to  the  earths  is  much  greater  in  the  amorphous  material.  Here  also 
tin?  glass  was  prevented  from  crystallizing  by  peculiarities  of  composition,  not  of  the  physical  condi- 
tions to  which  it  was  subjected. 

3 Neues  Jahrbnch  fiir  Mineral.,  18(51),  p.  3C>;  ibid..  1ST.:,  p.  :>?. 


BASALTIC  GLASS.  161 

These  analyses  are  directly  comparable  with  those  of  the  basalt  and 
basaltic  obsidian  and  with  the  andesite  and  andesitic  obsidian  from  Clear 
Lake,  and  the  character  of  the  differences  is  manifestly  the  same.  In  each 
case  the  glass  is  comparatively  very  rich~in  alkalis  and  silica  and  contains 
only  a  little  lime  or  magnesia. 

inferences. — In  the  rocks  from  Amiata  and  the  Rossberg  only  small  blebs 
or  streaks  of  acid  glass  are  found.  At  Clear  Lake,  on  the  other  hand,  im- 
mense quantities  of  glass,  covering  large  areas,  accompany  crystallized  rocks 
in  such  a  manner  as  to  leave  no  doubt  of  their  direct  connection.  The 
nature  of  the  cases  is  the  same,  but  the  size  of  the  masses  is  very  different, 
and  I  am  not  aware  that  any  instance  has  ever  been  studied  in  which  areas 
of  glass  which  must  be  measured  by  the  square  mile  are  thus  connected 
with  crystallized  rocks  of  a  different  chemical  composition.  It  is  plain  from 
these  occurrences  that  associated  masses  of  very  different  chemical  composi- 
tion and  of  great  volume  sometimes  form  portions  of  the  same  eruptions. 
They  pass  over  into  one  another  by  transitions,  but,  whether  they  never 
have  been  more  thoroughly  mingled  than  they  now  are  or  whether,  having 
been  intimately  mingled,  they  have  separated  by  eliquation,  it  is  perhaps 
impossible  to  decide  at  present.  The  conditions  show  that  they  were  in 
contact  in  a  fluid  state  and  that  the  passage  from  the  crystalline  to  the 
amorphous  rocks  is  a  gradual  one. 

It  is  manifest  that,  in  the  case  of  these  comparatively  recent  and  super- 
ficial rocks,  the  crystallization  has  been  governed  by  the  chemical  compo- 
sition, for  the  glassy  and  crystalline  masses,  while  of  different  composition, 
have  been  subjected  to  physical  conditions  which  were  nearly  identical.  It 
cannot  be  doubted  that  there  are  many  cases  in  which  the  differences  in 
structure  of  massive  rocks  are  referable  to  chemical  variations  which  are 
perhaps  numerically  small.  Even  in  the  lavas  it  is  not  an  infrequent  thing 
to  find  rounded  masses  which  differ  greatly  in  rnineralogical  composition 
from  the  surrounding  mass,  and  yet  these  have  been  subjected  to  ex- 
actly the  same  physical  conditions  as  the  material  in  which  they  are  em- 
bedded. Even,  therefore,  if  no  chemical  difference  known  to  be  significant 
could  be  discovered,  it  would  inevitably  follow  that  such  a  difference  nev- 
ertheless existed,  for  variations  in  texture  must  be  due  to  variations  either 

MON  XIII— 11 


162  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

in  composition  or  in  the  physical  conditions  to  which  the  several  masses 
have  been  subjected.  A  few  tenths  of  1  per  cent,  of  carbon  in  iron  changes 
its  fusibility  and  texture  enormously  and  trifling  quantities  of  silica  or 
alumina  cause  immense  variation  in  the  fusibility  of  the  normal  bisilicate, 
iron  blast-furnace  slag.  It  is  well  known  that  when  furnace  men  desire  a  slag 
which  fuses  less  readily  than  this  they  do  not  dare  to  add  either  alumina 
or  silica,  because  either  raises  the  melting  point  so  rapidly.  Lavas,  which 
are  natural  slags,  must  be  affected  in  a  similar  way  bv  these  or  by  other 
substances,  such  as  titanium. 

Granitoid  and  porphyritic  texture. While  tll6  obsIdiailS   of   Clear  Lake  aild  of  the 

Rossberg  have  evidently  remained  amorphous  because  of  their  peculiar 
chemical  composition,  it  by  no  means  follows  that  had  they  been  cooled 
sufficiently  slowly  they  might  not  have  crystallized.  On  the  contrary,  the- 
ory and  experiment  alike  point  to  the  supposition  that  vitreous  substances 
will  always  crystallize  if  they  have  sufficient  opportunity.  This  is  gener- 
ally admitted. 

It  is  often  supposed  to  be  merely  an  extension  of  the  acknowledged 
tendency  to  crystallization  to  maintain  that,  if  glassy  magma  is  only  cooled 
slowly  enough,  the  result  will  be  a  mass  which  is  not  merely  holocrystal- 
line,  but  of  granitic  structure 

The  difference  between  typical  granular  texture  and  porphyritic  text- 
ure, however,  is  a  very  different  matter  from  the  distinction  between  holo- 
crystalline  and  glassy  structure,  a  fact  which  appears  to  have  escaped  the 
attention  of  many  lithologists.  The  conclusion  to  be  drawn  from  granular 
structure  is  that  various  minerals  crystallized  simultaneously,  while  the 
larger  mineral  constituents  of  porphyries  have  evidently  crystallized  in 
advance  of  the  groundmass  surrounding  them. 

If  a  substantially  homogeneous  fluid  cools  very  slowly  indeed,  the 
tendency  will  be  for  some  of  the  resulting  compounds  to  crystallize  in  ad- 
vance of  others,  and  therefore  to  attain  a  considerable  size  and  good  crvs- 
tallographic  development.  This  follows  both  from  theory  and  experiments 
familiar  to  every  chemist.  If  the  cooling  of  such  flifid  is  continued  at  a 
very  slow  rate,  the  interstices  must  fill  with  other  crystals  the  growth  of 
which  will  be  interfered  with  by  mutual  opposition  and  the  obstruction  of 


EOCK  STRUCTURE.  163 

the  earlier  crystals,  and  the  final  result  will  in  general  be  a  porphyry.  Only 
in  the  limiting  and  just  supposable  case  that  the  formation  of  the  various 
final  mineral  ingredients  of  a  rock  liberates  heat  at  exactly  the  same  rate 
can  they  all  crystallize  simultaneously  from  a  substantially  fluid  mass  and 
produce  a  granular  structure.  This  inference  is  strengthened  by  observa- 
tions on  typical  porphyries.  It  is  acknowledged  that  the  larger  crystals  of 
good  porphyries  antedate  eruption  and  have  been  formed  at  the  enormous 
pressures  which  must  prevail  at  the  sources  of  eruption.  Had  such  rocks 
never  been  ejected  and  had  they  cooled  in  place  at  an  almost  infinitesimal 
rate,  it  seems  to  me  that  only  porphyries  could  have  resulted  from  the  process. 
On  the  other  hand,  if  a  heterogeneous  but  more  or  less  intimately 
mingled  mass  is  acted  upon  by  chemically  active  solutions,  the  reaction 
yielding  heat  most  rapidly  will  vary  from  point  to  point  with  the  composi- 
tion. In  such  a  magma  a  granular  structure  would  naturally  result.  These 
are  the  conditions  attending  metamorphism,  and  highly  metamorphic  rocks 
are  typically  granular.  Eruptive  granular  rocks  (or  those  which  most  geol- 
ogists believe  to  be  eruptive)  frequently,  if  not  always,  exhibit  the  best  of 
evidence  that  they  are  by  no  means  of  uniform  composition,  and  have  there- 
fore never  been  thoroughly  or  substantially  fluid.  Portions  of  such  rocks 
a  few  inches  apart  present  differences  in  structure  and  mineralogical  com- 
position much  more  marked  than  those  observed  in  lavas.  The  differences 
can  be  due  only  to  physical  or  chemical  causes,  and.  since  so  closely  ad- 
joining portions  of  rocks  must  have  been  subjected  to  the  same  pressure 
and  must  have  cooled  at  the  same  rate,  the  only  possible  conclusion  is  that 
the  composition  changes.  These  variations  are  so  great  and  so  abrupt  as 
to  indicate  that  the  original  magma  was  not  substantially  fluid,  a  conclu- 
sion long  ago  reached  by  Scheerer.  A  lack  of  fluidity  and  of  homogeneity 
thus  characterizes  magmas  which  yield  granular  rocks.  This  partial  fusion 
cannot  be  in  general  the  result  of  pressure,  for,  while  it  is  certain  that  some 
magmas  would  yield  porphyries  if  cooled  at  depths  of  many  miles  below  the 
surface,  granular  rocks  of  analogous  composition  are  known  in  many  cases 
to  overlie  sedimentary  material  later  than  the  Archrean,  and  cannot  have  been 
subjected  to  pressures  so  great  as  those  under  which  the  magmas  of  the 
corresponding  porphyries  were  substantially  fluid. 


164  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

conclusions — It  will  readily  be  seen  to  be  a  consequence  of  the  above 
facts  that  granular  rocks  having  precisely  the  same  composition  as  porphy- 
ries cannot  have  been  so  highly  heated  as  the  latter  and  that  granular 
rocks  as  a  group,  unless  they  differ  from  the  porphyries  in  chemical  com- 
position far  more  than  has  hitherto  been  suspected,  cannot  have  been 
subjected  to  temperatures  on  the  whole  so  intense.  Differences  in  texture 
are  in  a  great  proportion  of  cases  certainly  due  to  differences  in  composi- 
tion, and,  even  if  one  were  to  find  a  continuous  column  of  rock  porphy- 
ritic  at  the  upper  end  and  gradually  passing  over  into  a  granitoid  mass  at 
the  lower  end,  the  occurrence  would  not  prove  that  the  difference  in  text- 
ure was  due  to  difference  in  pressure  and  rate  of  cooling,  unless  the  com- 
position were  also  proved  to  be  identical  (an  impossibility)  or  it  could  be 
shown  that  the  granular  rock  had  once  been  a  real  fluid  and  not  merely  a 
half-fused  mass  full  of  solid  particles  of  various  kinds.  Such  instances  as 
the  lavas  of  Clear  Lake,  the  mingled  granular  and  porphyritic  diorites  of 
the  Comstock,  and  many  exposures  of  granite  show  that  the  homogeneity 
of  any  single  body  of  massive  rock  cannot  be  taken  for  granted  and  that 
differences  of  composition  lead  to  differences  of  texture  almost  certainly 
greater  than  those  resulting  from  the  weight  and  slow  conduction  of  thou- 
sands of  feet  of  rock.1 

ORIGIN   OF   THE    MASSIVE    ROCKS. 

importance  of  the  subject. —  Granite  underlies  the  Coast  Ranges  and  the  Si- 
erra Nevada,  and  much  of  the  surface  of  these  ranges  is  flooded  with  lava. 
The  question  of  the  origin  of  these  rocks  is  of  great  importance  to  a  thor- 
ough discussion  of  the  ore  deposits,  for  it  is  from  the  granite  or  the  lava 
that  the  ore  is  most  likely  to  have  been  derived.  The  genesis  of  the  re- 

1 1  have  discussed  this  subject  more  fully  iu  a  paper  on  The  texture  of  massive  rocks:  Am.  Jour. 
Sci.,  '3d  series,  vol.  3:5,  1887,  p.  50.  Prof.  A.  Lagorio  has  published  a  very  valuable  memoir  on  the  nat- 
ure of  glass  base  and  on  the  process  of  crystallization  in  eruptive  rocks  (Tschermaks  mineral.  Mii- 
thcil.,  vol.  8,  1887,  p.  421).  This  paper  reached  me  after  the  transmission  of  this  volume.  The  author 
carefully  considers  both  the  chemical  and  physical  influences  affecting  the  tundeucy  to  crystallization. 
He  points  out  the  high  alkali  contents  of  the  glasses  and  reaches  the  conclusion  that  potassium  silicates 
are  the  last  to  solidify.  He  refers  granitoid  structure  to  the  sudden  consolidation  under  pressure  of 
supersaturated  solutions  of  several  salts.  This  does  not  seem  to  me  a  satisfactory  explanation.  Simul- 
taneous supersaturation  of  a  solution  of  several  silicates  seems  to  me  improbable,  as  docs  also  their 
simultaneous  precipitation  from  supersaturated  solution. 


ORIGIN  OP  MASSIVE  KOCKS.  165 

agents  in  which  the  ore  was  dissolved  previous  to  its  deposition  was  also, 
beyond  a  doubt,  closely  connected  with  the  origin  of  the  massive  rocks. 

Hypothesis  of  sedimentary  origin. —  As  is  well  known,  many  geologists  suppose 
not  only  granite,  but  all  eruptive  rocks,  to  be  products  of  the  more  or  less 
complete  fusion  of  the  sedimentary  strata.  On  this  supposition  there 
would  be  more  or  less  organic  matter  or  carbon  distributed  throughout  all 
rocks,  and  this  material  would  exercise  a  most  important  influence  on  sub- 
terranean chemical  reactions.  While  the  writers  referred  to  maintain  that 
the  massive  rocks,  without  exception,  have  passed  through  the  sedimentary 
state,  all  are  agreed  that  the  material  of  which  they  are  composed  must 
have  originally  formed  a  portion  of  the  primeval  massive  crust  of  the 
globe.  Most  of  them  are  of  the  opinion  that  these  primeval  rocks  are  so 
deeply  buried  beneath  their  own  accumulated  waste  as  to  be  totally  inac- 
cessible and  that  we  know  nothing  of  their  character.  The  opinion  here 
sketched  in  its  leading  features  is  an  old  one,  and,  though  a  large  number 
of  leading  geologists  dissent  from  it,  it  has  found  many  able  defenders. 
These  seem  to  me  to  have  overlooked  some  objections  and  to  have  general- 
ized too  broadly  from  certain  analogies.  It  is  difficult  to  understand  how 
on  a  globe  continually  .affected  by  upheaval  and  subsidence  the  rocks  un- 
derlying the  sedimentary  material  can  ever  be  entirely  buried.  It  is 
equally  difficult  to  imagine  any  means  by  which  the  primeval  rocks  can 
have  been  reduced  to  a  clastic  state  at  the  enormous  depth  called  for  by 
the  hypothesis,  a  deptli  of  at  least  twenty  miles  from  the  surface. 

Primeval  conditions. —  Geologists  and  physicists  are  substantially  agreed 
that  the  earth  was  once  an  intensely  heated,  plastic  or  fluid  spheroid.  This 
I  will  assume  to  be  true.  When  water  began  to  condense  on  the  cooling 
globe  there  were  of  course  no  sediments.  Even  as  they  first  solidified  the 
rocks  cannot  have  been  absolutely  level,  so  that  some  portions  of  the 
surface  were  more  exposed  than  others.  For  the  sake  of  simplicity  in  rea- 
soning, one  may  first  consider  what  would  have  happened  after  the  first 
oceans  formed,  had  there  been  no  such  thing  as  upheaval  and  subsid- 
ence. It  is  clear  that  all  the  more  elevated  portions  of  the  original  surface 
.of  the  globe  would  have  beeu  cut  down  by  erosive  processes  and  that  the 
entire  globe  would  have  been  eventually  covered  by  a  shallow  ocean,  the 


166  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

bottom  of  which  would  have  been  in  general  a  sedimented  area.  In  certain 
localities  one  may  suppose  that  oceanic  currents  might  have  cut  through 
this  stratum  of  sediment  and  eroded  the  underlying  primeval  rocks  to  some 
extent,  but  it  is  certain  that  action  of  this  description  would  soon  find  a 
limit,  and  that  thereafter  no  sensible  mechanical  action  would  be  exerted 
on  the  primeval  rocks.  Consequently,  the  quantity  of  sediment  could 
never  increase  perceptibly  beyond  a  certain  fixed  and  very  moderate  limit. 

Effect  of  upheavrj^. — If  upheaval  were  now  supposed  to  be  introduced  into 
terrestrial  economy,  portions  of  the  universal  sedimented  area  would  be 
raised  into  continents  and  would  undergo  erosion.  The  stratum  of  sedi- 
ment having  been  removed,  the  primeval  rock  would  again  be  exposed  and 
its  degradation  would  increase  the  total  amount  of  sedimentary  material. 

If  upheaval  were  confined  to  certain  areas  and  were  a  continuous 
process,  while  corresponding  subsidence  took  place  in  other  and  distinct 
areas,  primeval  rocks  would  continue  to  be  exposed  in  continental  regions, 
at  least  for  a  very  long  time.  If  upheaval  and  subsidence  were  to  alter- 
nate in  the  same  areas,  but  if  in  certain  regions  the  upheavals  were  on  the 
whole  somewhat  in  excess  of  the  subsidences,  primeval  rocks  would  appear 
at  the  surface  of  these  areas  from  time  to  time  and  the  total  quantity  of 
sediment  on  the  globe  would  at  these  times  receive  accessions. 

Upheavals  and  subsidences  could  alternate  and  balance  one  another 
on  each  portion  of  the  globe  only  if  the  influences  tending  to  produce  these 
movements  were  everywhere  exactly  balanced.  The  mere  fact  that  the 
poles  receive  less  heat  than  the  equatorial  regions  establishes  a  difference 
of  physical  conditions  on  various  portions  of  the  earth,  which  certainly  in- 
fluences erosion  and  cannot  but  affect  changes  of  level.  However  complex 
and  remote  the  connection  may  be  between  upheaval  and  evaporation,  some 
relation  certainly  subsists  between  them,  and  it  is  not  possible  that  on  a 
globe  like  ours  there  should  not  be  a  tendency  to  a  greater  prevalence  of 
uplifts  in  some  regions  than  in  others. 

Bearing  of  Dana's  continental  theory It    is  deal*  that,    if    ProfeSSOl*  1  hum's  tllCOry 

of  the  permanence  of  continental  areas  is  correct,  it  substantiates  the  con- 
clusion drawn  above,  that  there  are  areas  in  which  the  tendency  to  upheaval 
on  the  whole  exceeds  the  tendency  to  subsidence.  There  is  much  evidence 


UPHEAVALS.  167 

in  favor  of  Professor  Dana's  theory,  though  some  geologists  do  not  accept 
it.  If  tills  theory  were  absolutely  disproved,  it  would  still  be  impossible 
to  suppose  that  upheaval  and  subsidence  everywhere  exactly  balance  each 
other  in  the  long  run.  If  continents  once  existed  where  the  great  oceans 
now  lie,  a  perfect  history  of  the  earth  would  show  that  there  were  conti- 
nents in  some  parts  of  the  world  through  larger  portions  of  geological  time 
than  in  other  recrions.  In  regions  where  the  total  erosion  has  exceeded  the 

o  o 

total  sedimentation,  the  original  crust  must  almost  certainly  be  exposed. 

Bearing  of  principle  of  hydrostatic  equilibrium Nothing    ill     geology   is   IBOrC     CCl'taill 

than  that  the  earth  is  very  nearly  in  a  condition  of  hydrostatic  equilibrium,1 
and  it  is  the  maintenance  of  this  equilibrium  which  necessitates  upheaval 
and  subsidence.  This  is  perfectly  evident  if  the  interior  of  the  earth  is  fluid. 
It  is  also  true  if  the  earth  is  solid  to  the  center  and  as  rigid  as  steel  or 
glass;  for  a  mass  as  large  as  the  earth  of  either  of  these  substances  could 
not  maintain  a  shape  diverging  considerably  from  a  form  of  fluid  equilibri- 
um for  any  length  of  time.  Even  masses  of  metal  of  a  few  tons  (e.  g., 
metallic  mirrors  for  astronomical  purposes)  undergo  deformations  by  their 
own  weight.  So  also  will  a  slab  of  marble  supported  at  its  extremities, 
and,  in  short,  the  flow  of  solids  in  general  is  a  well  recognized  fact.2  Now, 
if  the  earth  is  a  solid,  highly  viscous  mass,  as  Thomson  and  Darwin  have 
concluded,  the  effect  of  the  subsidence  of,  say,  a  sedimented  oceanic  area 
must  be  felt  to  the  center  of  the  earth,  and  the  earth  from  the  center  to  the 
surface  must  partake  in  an  upheaval.  If,  on  the  other  hand,,  the  globe  con- 
sists of  a  solid  shell,  which  is  growing  thicker,^arid  a  fluid  ball  upon  which 
the  shell  floats,  the  effect  of  the  subsidence  of  a  given  area  must  be  to 
depress  the  fluid  magma  underlying  this  area  and  to  raise  some  other 
column  of  the  fluid  under  eroded  regions.  Even  in  this  case,  then,  at  least 
the  superficial  portion  of  the  fluid  ball  partakes  in  the  movement  attending 
upheaval  and  subsidence. 

1  l.abbage,  I  believe,  was  the  first  to  point  out  this  now  familiar  fact. 

1  In  discussing  the  nuestion  of  the  solidity  of  the  earth,  geologists  seem  sometimes  to  forget  that 
timi'  outers  into  the  conception  of  viscosity.  The  earth  may  be  as  rigid  as  steel  with  reference  to  forces 
which  rapidly  change  thoir  directions  like  those  exerted  by  the  sun  and  moon,  but  as  plastic  as  putty 
tu  much  smaller  stresses  acting  continuously  through  long  periods  of  time  in  a  single  direction.  The 
rigidity  of  the  earth  claimed  for  it  by  physicists  is  not  inconsistent  with  the  flexure  of  strata.  So  a 
stick  of  sealing-wax  may  be  slowly  contorted  by  its  own  weight,  but  a  smart  blow  will  break  it  like 
glass. 


168  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC!  SLOPE. 

consequent  effects  of  upheaval. — Granting,  as  one  inevitably  must,  that  there  are 
areas  over  which  there  is  a  tendency  to  the  prevalence  of  upheavals  over 
subsidences,  the  layer  of  a  supposed  fluid  interior  of  the  globe  which  con- 
gealed to-day  on  the  under  surface  of  the  crust  in  such  areas  must  rise 
gradually  or  intermittently  and  will  be  exposed  to  the  air  at  some  remote 
future  period.  Or  if  the  globe  is  a  viscous  solid,  the  plastic  mass  beneath 
the  lowest  sediments  in  areas  of  predominant  upheaval  must  be  rising  to- 
ward the  sui-face.  In  either  case  it  would  appear  from  the  above  that  the 
exposure  at  the  surface  of  the  earth  of  material  upon  which  no  ray  of  light 
has  ever  fallen  since  the  outer  layer  of  the  earth  congealed  must  be  of  daily 
occurrence. 

Logical  consequences  of  sedimentary  hypothesis TllC  Supposition  that  all  the  material 

now  exposed  to  view  has  passed  through  the  sedimentary  condition  seems 
to  be  conceivable  only  in  one  way.  It  implies  the  hypothesis  that  upheaval 
and  subsidence  are  substantially  superficial  phenomena,  in  which  the  inte- 
rior of  the  earth  has  no  part.  It  supposes  that  the  sediments  which  subside, 
off  a  coast  perhaps,  afterwards  flow  laterally  and  again  ascend  to  the  sur- 
face at  some  other  point,  perhaps  in  a  fluid  or  plastic  state,  as  lava  or  granite. 
This  is  a  condition  of  things  which  cannot  always  have  existed.  The  pri- 
meval massive  rocks  must  evidently  have  been  exposed  until  the  entire 
quantity  of  material  which  has  ever  been  brought  into  the  form  of  sedi- 
ment was  eroded  from  their  surfaces,  and,  during  that  period,  the  interior 
of  the  earth  must  have  partaken  in  the  movements  of  upheaval  and  subsi- 
dence. The  greater  the  quantity  of  matter  which  is  assumed  to  have  been 
at  some  time  sedimentary,  the  longer  must  the  exposure  of  primeval  mass- 
ive rocks  have  continued  and  the  more  difficult  does  it  become  to  under- 
stand how  the  interior  can  ever  have  ceased  to  be  affected  by  upheaval  and 
subsidence.  The  geologists  who  take  this  view  are  compelled  to  assume  an 
enormous  thickness  for  sedimentary  material,  and  they  must  consequently 
also  suppose  that  primitive  rocks  have  been  exposed  during  an  enormous 
period.  The  fact  appears  to  be,  however,  that  the  supposed  failure  of  the 
earth's  interior,  say  beneath  a  mean  depth  of  twenty  miles,  to  partake  in 
the  movements  of  upheaval  and  subsidence  is  totally  inexplicable  on 
mechanical  principles.  Some  geologists  have  hotly  assailed  physicists  for 


EEOSION.  1 69 

maintaining  that  no  great  part  of  the  earth  can  be  fluid.  The  hypothesis 
that  only  a  superficial  layer  of  the  globe  is  affected  by  upheaval  and  subsi- 
dence appears  to  me  to  imply  that  beneath  this  thin  shell  the  earth  is  not 
the  highly  viscous  solid  of  Sir  William  Thomson,  but  a  body  of  absolute, 
ideal,  and  impossible  rigidity,  for  only  then  could  it  fail  to  share  in  the  def- 
ormation of  the  surface. 

The  problem  viewed  as  one  of  erosion. Tll6   aVCl'age   tllicklieSS   of  tll6  Sedimentary 

rocks  is  in  my  opinion  often  greatly  exaggerated.  It  is  true  that  if  the 
greatest  thicknesses  of  the  formations  are  added  they  form  an  enormous 
total ;  but  we  all  know  that  sediments  are  thickest  near  shore  lines  and  dis- 
appear altogether  at  a  distance  from  the  shore.  According  to  those  author- 
ities who  maintain  that  even  the  igneous  rocks  are  fused  sediments,  of  course 
the  later  sedimentary  rocks  are  composed  of  the  same  material  which  en- 
tered into  earlier  strata.  That  this  is  to  a  large  extent  the  case  is  evident. 
Clearly,  however,  it  must  also  have  been  the  case  to  some  extent  from  the 
date  of  the  first  upheaval  after  oceans  formed  on  the  surface  of  the  globe. 
As  time  went  on  the  exposed  areas  of  the  primitive  rocks  must  have  de- 
creased while  a  larger  and  larger  proportion  of  freshly  formed  rocks  was 
produced  at  the  expense  of  the  older  beds.  After  a  certain  time  the  addi- 
tions to  the  total  amount  of  detrital  material  in  a  given  period,  say  one 
thousand  years,  would  be  very  small,  and  from  that  time  onward  the  quan- 
tity of  detrital  material  would  remain  nearly  constant.  Now,  if  one  supposes 
the  average  thickness  of  sedimentary  rocks  at  some  past  epoch  to  have  been 
only  one  mile,  it  is  evident  that  only  a  minute  proportion  of  any  land  area 
similar  to  the  present  continents,  or  even  of  much  bolder  configuration  than 
these,  could  be  occupied  by  exposed  primeval  rocks.1  If  an  average  thick- 
ness of  one  mile  of  sedimentary  material  would  reduce  the  area  of  primitive 
rocks  to  a  very  small  one,  how  is  it  possible  to  account  for  the  formation 
of  twenty  times  this  quantity  of  detritus  ?  I  do  not  think  it  can  be  done. 
character  of  the  process  of  degradation. — The  hypothesis  that  this  almost  incredible 
quantity  of  detrital  material  exists,  as  applied  by  advocates  of  the  sedi- 
mentary origin  of  massive  rocks,  involves  the  assumption  that  degradation 

1  Gaiinctt's  fsl  imato  of  the  mean  elevation  of  the  United  States,  excluding  Alaska,  is  2,000  feet,  say 
half  a,  mile.     LoipoHU's  estimate  for  Europe  is  '297  meters,  or  975  feet,  say  a  sixth  of  a  mile. 


170  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

of  primitive  rocks  came  to  a  complete  close.  The  last  exposed  primitive 
rocks  must  have  subsided  and  have  been  buried  under  sediments  formed 
from  pre-existing  strata,  and  this  subsidence  must  have  exceeded  in  amount 
the  sum  of  all  the  upheavals  to  which  they  have  since  been  subjected- 
This  seems  to  me  a  very  artificial  hypothesis,  quite  out  of  harmony  with 
those  theories  which  have  been  found  to  accord  best  with  other  geological 
facts.  It  is  seldom  that  we  find  in  nature  abruptly  arrested  processes,  such 
as  this  is  supposed  to  be,  excepting  where  these  are  reversible,  which  this 
is 'not.  It  is  more  natural  to  suppose  that  the  area  of  primitive  rocks 
diminished  progressively  without  ever  being  completely  or  irrevocably 
buried.  Thus,  in  the  second  million  of  years  after  oceans  came  into  ex- 
istence, one  may  imagine  half  as  much  fresh  detritus  to  have  formed  as  in 
the  first  million  years;  in  the  third  such  period  half  as  much  as  in  the 
second,  and  so  on  to  the  present  day.  Had  this  been  the  actual  case,  the 
total  amount  of  sediment  at  the  end  of  an  infinite  time  would  differ  infi- 
nitely little  from  twice  the  quantity  of  sedimentary  material  at  the  end 
of  the  first  million  years,  and  infinitesimal  areas  of  primeval  rocks  would 
still  remain  exposed  even  after  the  process  had  continued  for  an  infinite 
time.  In  using  this  numerical  illustration  I  do  riot  of  course  intend  to  imply 
that  the  particular  numbers  selected  are  in  themselves  probable.  The 
length  of  the  successive  periods,  in  each  of  which  the  total  quantity  of 
fresh  detritus  derived  from  the  primeval  massive  rocks  was  half  that  sim- 
ilarly produced  in  the  preceding  period,  may  have  varied  regularly  or 
irregularly.  But  I  do  maintain  that  neither  theory  nor  observation  affords 
any  ground  for  the  hypothesis  that,  during  some  one  period  in  the  earth's 
history,  the  entire  area  of  primeval  rocks  was  obliterated,  never  to  reappear 
If  I  am  right  in  doing  so,  it  is  improbable  that  the  primeval  rocks  have 
been  or  ever  will  be  entirely  concealed  from  view  at  all  points  on  the  earth's 
surface  during  any  considerable  time.  In  other  words,  contemplation  of 
the  process  of  erosion  leads  to  the  same  result  as  was  reached  by  consid- 
ering the  mechanism  of  upheaval. 

Relations  of  granite. — The  observations  which  are  usually  cited  in  support  of 
the  sedimentary  origin  of  lavas  depend  upon  the  relation  of  granites  to  other 
rocks.  That  granites  are  sometimes  so  connected  with  crystalline  schists 


PRIMEVAL  ROCKS.  171 

as  to  lead  to  the  belief  that  they  pass  over  into  one  another  is  certain.  It 
is  also  maintained  by  many  geologists  (erroneously,  as  I  believe)  that  cases 
occur  in  which  a  series  of  transitions  exists  from  granite  to  glassy  lavas.  If 
both  these  propositions  were  correct,  it  would  follow  that  a  transformation 
of  sediments  into  lavas  would  be  possible  under  certain  conditions,  but  it 
would  not  follow  that  this  is  the  usual  history  of  lavas  or  even  that  it  is 
the  history  of  a  single  lava.  Neither  does  it  follow  that  because  some 
granites  are  metamorphosed  sediments  all  granites  are  of  this  class. 

Possible  character  of  primeval  rocks. TllC   oldest    Sedimentary  1'Ocks     COmpOSO   the 

Archaean  wholly  or  in  part.  These  rocks  are  also  much  more  uniform  in 
composition  than  later  stratified  rocks.  They  must  have  been  derived  in 
great  part  from  the  primeval  rocks,  which  therefore  possessed  the  same 
mean  composition  as  the  schists.  This  composition  is  substantially  iden- 
tical with  that  of  granite.  Hence,  a  rock  chemically  similar  to  granite 
formed  the  primeval  surface.  This  rock  must  also  have  formed  at  high 
temperatures,  very  slowly,  and  under  great  pressure.  It  must  inevitably 
have  been  chiefly  crystalline,  and  all  analogy  and  experiment  lead  to  the 
belief  that  it  can  have  contained  no  glass.  It  must  have  been  a  holocrys- 
talline  porphyry  or  a  granular  rock.  The  atmosphere  previous  to  the 
solidification  of  the  surface  of  the  globe  must  have  contained  at  least  as 
much  water  as  the  ocean  now  holds,  as  well  as  most  of  the  carbon  now  present 
in  limestones,  coal  beds,  etc.  The  pressure  of  this  atmosphere  must  have 
been  at  least  three  or  four  thousand  pounds  per  square  inch  and  the  boiling 
point  of  water  must  have  been  correspondingly  high.  When,  or  soon  after, 
the  temperature  at  the  surface  sank  to  the  critical  point  of  water  (580° 
C.,  Mendelejeff),  and  therefore  while  the  surface  was  still  red-hot,  water 
must  have  condensed  upon  it.  Judging  from  what  is  known  experiment- 
ally of  igneo-aqueous  fusion,  conditions  more  favorable  to  this  process  could 
not  be  imagined.  Now  there  is  much  reason  to  suppose  that  granite  has 
been  produced  by  igneo-aqueous  fusion.  It  is  therefore  in  the  highest 
degree  probable  that  the  terrestrial  surface  when  the  earth  first  ceased 
to  glow  was  granite,  very  probably  accompanied  to  some  extent  by  allied 
plagio  clastic  rocks.  It  is  far  from  impossible  that  portions  of  it  may  have 
had  a  gneissoid  structure. 


172  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

The  foregoing  paragraph  contains  no  novel  statement.  Scrope,1  in 
1825;  MacCulloch,2  in  1831;  and  Elie  de  Beaumont,3  in  1847,  all  maintained 
that  the  primeval  rock  from  which  the  strata  are  derived  must  have  been 
granitic.  In  1859  Mr.  Daubree4  entered  more  fully  into  the  physical  theory 
of  the  formation  of  the  primitive  rocks.  Taking  as  a  basis  Humboldt's 
estimate  of  the  mean  depth  of  the  ocean  (3,500  meters),  he  calculated  that 
the  barometric  pressure  of  the  sea  water  alone  in  the  form  of  vapor  would 
amount  to  almost  exactly  two  hundred  and  fifty  atmospheres,  or  say  3,700 
pounds  per  square  inch.  Later  estimates  of  the  area  and  depth  of  the  sea 
diminish  this  figure  somewhat,  but  only  to  the  extent  of  about  a  hundred 
pounds."'  When  the  temperature  of  the  earth  was  too  high  to  permit  of  the 
condensation  of  water,  this  pressure  wns  farther  augmented  by  other  vapors 
and  gases.  The  purely  igneous  rocks  formed  prior  to  the  condensation  of 
any  water,  as  Daubree  infers,  must  have  been  changed  by  the  action  of  the 
water  first  precipitated  at  very  high  temperatures  and  pressures  into  a  mass 
of  crystallized  minerals,  exactly  as  in  his  own  experiments  in  sealed  tubes 
crystals  were  developed  from  amorphous  materials.  Inquiring  whether  the 
earliest  aqueous  precipitation  corresponds  to  the  period  of  the  formation  of 
granite,  he  replies  that  we  cannot  affirm  this  in  an  absolute  manner,  but 
may  presume  it.  This  presumption  of  Mr.  Daubree,  previously  indicated 
by  others  on  less  satisfactory  grounds,  seems  to  me  to  gain  greatly  in  force 
by  the  reasons  which  I  have  adduced  above.  My  argument  shows  it 
utterly  improbable  that  the  rocks  which  antedate  the  formation  of  consid- 
erable seas  should  even  now  be  everywhere  concealed,  while  it  is  well 
known  that  the  lowest  visible  rocks  the  world  over  are  granitic.  In  1879, 
again,  Mr.  R.  Mallet0  speculated  upon  the  character  of  the  earliest  seas.  He 

1  Considerations  ou  Volcanoes  Leading  to  tlio  Establishment  of  a  New  Theory  of  the  Earth,  quoted 
by  Dr.  Hunt,  Origiu  of  Crystalline  Rocks,  sec.  17. 

*  System  of  Geology,  vol.  2,  p.  88.  "That  very  granite,"  he  adds,  "may  be  visible;  but  we  can- 
not as  yet  distinguish  it  from  the  many  successive  ones  which  have  acted  in  the  elevation  of  the 
strata." 

3  Bull.  Soc.  g<Sologiqne  France,  2d  series,  vol.  4,  pp.  1321  et  seq.      He  regards  granite  as  formed  by 
igneo-aqueous  fusion  and  speaks  (p.  1327)  of  "the  first  granitic  crust  of  the  terrestrial  globe." 

4  Etudes  et  expe>.  syuth.  stir  le  me'tain  :  Ann.  des  mines,  5th  series,  vol.  Ifi,  p.  471. 

15  Dr.  Kriimmel's  revision  of  the  question  of  the  total  quantity  of  water  in  the  ocean  (extract  from 
a  note  to  the  Gottiugen  Academy,  Nature,  vol.  19,  1879,  p.  348)  leads  to  about  3,584  pounds  per  square 
inch. 

6  Quart.  Jour.  Geol.  Soc.  London,  vol.  36,  1880,  p.  112. 


PEIMEVAL  ROCKS.  173 

deduced  the  conditions  as  Daubrt'e  had  done  and  pointed  out  the  "bearing  of 
the  critical  point  of  water.  But  the  chief  application  which  he  makes  of  the 
results  is  in  the  endeavor  to  account  for  the  great  quantity  of  detrital  mate- 
rial in  existence.  He  points  out  that  the^degradation  of  elevations  would  be 
more  rapidly  effected  by  heated  waters  than  by  cold  ones,  and  infers,  as  I 
understand  him,  that  hot  waters  would  also  ultimately  yield  a  greater  quan- 
tity of  detritus  than  cold  waters.  The  latter  of  these  propositions  does  not 
appear  to  me  to  follow  from  the  former  or  from  Mr.  Mallet's  arguments. 
It  would  seem  to  me  certain  that  the  maximum  accumulation  of  clastic 
material  would  be  more  rapidly  approached  were  the  water  hot,  but  that  this 
maximum  would  be  a  similar  quantity  whether  the  water  were  hot  or  cold. 

It  is  perhaps  unnecessary  to  point  out  that  if  the  purely  igneous  super- 
ficial layer  ot  fhe  earth's  mass  was  converted  into  a  crystalline  rock  resem- 
bling granite  at  enormous  pressures  and  at  temperatures  approximating  to 
500°  C.  the  quantity  of  water  in  the  fluid  state  which  was  instrumental  in 
the  transformation  must  have  been  comparatively  small,  for  the  great  press- 
ure was  due  to  the  fact  that  most  of  the  water  formed  a  gaseous  constituent 
of  the  atmosphere.  This  accords  with  the  views  of  Scheerer  and  subsequent 
investigators,  that  no  great  quantity  of  water  is  needed  to  render  aqueo- 
igneous  fusion  possible.  Sedimentation  must,  therefore,  at  this  period  have 
been  an  extremely  subordinate  phenomenon.1 

There  is  thus  every  reason  to  suppose  that  the  original  massive  rocks 
were  granitic  in  composition  and  in  texture.  The  fact  that  eruptive  gran- 
ites were  ejected  in  later  times  only  shows  that  at  certain  depths  beneath 
the  surface  the  conditions  of  heat,  pressure,  and  moisture  which  once  pre- 
vailed upon  the  surface  were  repeated.  That  detritus  from  the  original 
granite  under  great  pressure  and  at  high  temperature  may  also  sometimes 
be  metamorphosed  into  a  material  similar  to  the  original  granite  is  cer- 

'  As  the  temperature  sank  still  further  and  oceans  began  to  accumulate,  the  water  must  have  heen 
highly  charged  with  mineral  matter.  It  is  to  this  later  period  that  Dr.  Hunt,  who  accepts  Dau- 
brcVs  exposition  of  the  action  of  the  earliest  condensed  water,  ascribes  the  formation  of  the  Arclm-an 
whists  as  chemical  precipitates.  In  the  text  I  am  Lot  concerned  with  the  formation  of  the  crystalline 
schists,  but  I  wish  to  state  that  it  appears  to  me  impossible  to  suppose  no  crystalline  precipitates  to 
have  been  deposited.  I  do  not  doubt  that  such  were  formed  in  a  manner  nearly  or  quite  identical  with 
that  which  Dr.  Hunt  maintains.  As  appears  in  a  preceding  chapter,  however,  I  cannot  agree  with  this 
brilliant  thinker  in  ascribing  nearly  all  crystalline  stratified  rocks  to  this  process,  nor  can  I  believe 
that  anything  like  the  entire  Archiean  has  been  thus  produced. 


174  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

tainly  not  surprising.  Neither  of  these  facts  even  tends  to  prove  that  the 
primeval  rocks  were  not  granitic  or  that  they  are  now  nowhere  exposed. 
How  primeval  granite  is  to  be  discriminated  in  all  cases  and  with  certainty 
from  that  which  was  erupted  in  subsequent  geological  ages  or  from  highly 
metamorphosed  rocks  is  another  question,  to  which  a  definite  answer  cannot 
yet  be  given.  At  present  general  evidence  only  is  attainable. 

California  granit«. — Granite  underlies  the  greater  part  of  the  State  of  Cali- 
fornia. This  granite  must  be  exposed  to  very  different  depths.  The  Sierra 
has  been  undergoing  erosion  ever  since  the  early  Paleozoic,  and  on  the  lower 
portions  of  its  eastern  flanks  are  metamorphosed  strata  not  younger  than 
the  early  Mesozoic.  At  the  McCloud  River  the  Carboniferous  also  appears 
to  rest  on  granite.  The  granite  of  the  Coast  Ranges  has  been  covered  by 
sediments  a  large  part  of  the  time  which  has  elapsed  since  the  Paleozoic 
and  has  been  far  less  exposed  to  erosion  than  that  of  the  Sierra;  yet 
granites  from  the  various  localities  are  almost  indistinguishable.  Though 
there  may  be  granites  within  this  area  of  different  origins  and  ages,  I  ran 
see  no  reason  to  suppose  that  the  great  underlying  mass  is  not  substantially 
one  It  is  probably  continuous  with  the  granitic  areas  of  Idaho  and  Arizona 
and  is  too  extensive  to  be  regarded  as  an  eruption  or  a  series  of  eruptions. 
Were  it  metamorphic,  evidences  of  the  fact  would  probably  be  frequent, 
whereas,  so  far  as  is  known,  there  are  very  few  localities  in  the  State  that 
suggest  this  derivation.  While  both  metamorphic  and  eruptive  granites  will 
probably  be  found,  the  main  mass  must  be  at  least  as  old  as  the  Archrean, 
and,  while  I  do  not  assert  positively  that  it  is  primitive  granite,  this  appears 
to  me  far  more  probable  than  any  other  hypothesis.  As  was  pointed  out 
above,  the  formation  of  more  or  less  gneissoid  rock  probably  accompanied 
that  of  the  primeval  granite  and  the  presence  of  such  material  in  a  granitic 
area  does  not  prove  that  it  is  not  primeval.1 

California  lavas. — The  lavas  have  unquestionably  come  up  through  the 
granite  and  are  of  infragranitic  origin.  There  is  no  direct  evidence  what- 

'A  portion  of  tlie  primeval  crystalline  rocks,  though  perhaps  a  small  one,  was  probably  plagio- 
clastic.  It  would  be  difficult  otherwise  to  account  for  the  quantity  of  soda  in  t.h>'  clastic  rocks.  If 
Professor  l.a^orio  is  correct,  as  he  seems  to  me  to  be,  in  asserting  iliat  sodium  silicates  separate  from 
magmas  morn  readily  than  potassium  compounds,  it,  would  seem  that  oitlmclaso  should  have  predom- 
inated in  the  outer  crust  of  the  earth,  or  in  the  primeval  grauitie  rocks,  and  that  plagioclase  should 
have  predominated  in  the  iiifragranitic  rocks,  or  in  the  lavas.  This,  of  course,  accords  with  observation. 


UNIVERSITY 


CALIFORNIA  GRANITE. 

ever  that  the  material  of  which  they  are  composed  has  ever  yet  been  de- 
posited from  water,  and,  on  the  contrary,  there  are  weighty  reasons  for 
supposing  that  they  have  ascended  through  primeval  rocks.  The  absence 
of  hydrocarbons  in  a  part  of  volcanic  emanations  is  also,  as  Bunsen  showed, 
a  very  strong  argument  against  the  supposition  that  any  organic  matter  (or 
any  sedimentary  rocks  of  later  date  than  the  origin  of  life)  exists  at  the 
sources  of  volcanic  activity.  An  argument  in  favor  of  the  sedimentary 
origin  of  lavas  is  often  drawn  fro:n  the  supposed  great  variations  in  the 
composition  of  these  rocks.  This  seems  at  first  sight  to  be  justified  by  the 
literature  of  lithology,  but  those  who  have  specially  occupied  themselves 
with  that  branch  of  geology  are  well  aware  that  the  uniformity  of  eruptive 
porphyries  is  astonishing  and  that  typical  rocks  are  the  rule  the  world  over. 
In  geological  reports  hundreds  of  square  miles  of  a  normal  lava  will  be 
described  in  a  paragraph,  while  a  few  square  yards  of  some  abnormal, 
highly  exceptional  variety  of  the  rock  will  require  pages  of  description  and 
discussion.  The  literature  of  the  subject  is  thus  apt  to  convey  a  false  im- 
pression. 

conclusions. — The  arguments  presented  as  to  the  origin  of  the  massive 
rocks  of  California  may  be  briefly  summarized.  If  the  mechanism  of  up- 
heaval and  subsidence  is  considered,  it  seems  impossible  that  rocks  from 
beneath  the  accumulation  of  clastic  material  should  not  often  be  brought 
to  the  surface.  If  the  mechanism  of  erosion  is  considered,  i  t  appears  most 
improbable  that,  through  degradation  in  any  combination  with  subsidence, 
the  entire  area  of  primeval  rocks  should  ever  disappear  for  any  length  of 
time.  The  deepest-seated  rocks  known  are  granitic.  If  the  conditions 
attending  the  earliest  precipitation  of  water  on  the  earth's  surface  be  consid- 
ered, these  conditions  seem  to  be  those  known  experimentally  to  favor  the 
production  of  crystalline  minerals  and  which  are  believed  on  good  grounds 
to  be  those  attending  the  formation  of  granite.  The  evidence  in  California 
is  all  in  favor  of  the  hypothesis  that  the  main  mass  of  the  underlying  granite 
is  primeval,  or  that  it  antedates  the  formation  of  extensive  oceans,  and  that 
it  is  free  from  organic  matter.  The  lavas  come  from  beneath  the  granite 
and  are,  a  fortiori,  thoroughly  Azoic. 


CHAPTER  V. 

STRUCTURAL    AND     HISTORICAL    GEOLOGY    OF    THE 

QUICKSILVER  BELT.1 

General  results. —  No  attempt  has  been  made  in  the  present  investigation 
thoroughly  to  elaborate  the  general  geology  of  the  entire  area  in  which 
the  quicksilver  deposits  occur,  but,  in  addition  to  what  has  been  made 
known  by  other  geologists  on  this  subject,  it  was  found  indispensable  for  a 
proper  discussion  of  the  quicksilver  deposits  further  to  _elucidate  some  of 
the  more  important  structural  and  historical  relations  of  the  rocks  inclosing- 
them.  Such  facts  bearing  upon  the  general  geology  of  these  ore  deposits 
as  are  now  known  will  be  presented  in  this  chapter  in  chronological  ar- 
rangement Their  bearing  will  perhaps  be  clearer  if  the  reader  is  at  once 
put  in  possession  of  some  of  the  main  conclusions  reached,  which  are  as 
follows : 

The  Coast  Ranges  experienced  a  great  upheaval  (the  first  traced) 
probably  about  the  close  of  the  Neocomian,  this  being  the  same  disturb- 

1  Messrs.  Antisell,  Blake,  and  New  berry  contributed  valuable  papers,  containing  information  on  the 
geology  of  the  Coast  Ranges,  to  the  Pacific  Railroad  reports.  Under  Professor  Whitney,  Messrs. 
Brewer,  Gabb,  King,  and  others'studied  this  area.  Their  results  are  to  be  found  in  the  well  know  n 
publications  of  the  California  survey.  Mr.  Jules  Marcou  has  also  written  on  the  subject,  especially  in  the 
Bulletin  of  the  French  Geological  Society,  vol.  2,  1883,  p.  407,  and  the.  Proceedings  of  the  California 
Academy  of  Sciences  contain  numerous  pertinent  papers.  I  have  endeavored  to  make  such  use  of  this 
material  as  seemed  advisable.  Dr.  C.  A.  White  has  co-operated  with  me  in  the  study  of  the  general 
geology  of  the  region,  his  standpoint  being  that  of  the  paleontologist.  The  importance  of  some  of 
the  results  reached  led  us  to  publish  a  part  of  them  in.  advance  of  this  memoir.  The  papers  in  -which 
these  were  announced  are:  On  the  Mesozoic  and  Ceuozoic  Paleontology  of  California,  by  C.  A.  White 
(Bull.  U.  S.  Geol.  Survey  No.  13);  On  New  Cretaceous  Fossils  from  California,  by  C.  A.  White  (Bull. 
U.  S.  Geol.  Survey  No.  &2),  and  Notes  on  the  Stratigraphy  of  California,  by  G.  F.  Becker  (Bull.  U.  S. 
Geol.  Survey  No.  19).  I  have  also  used  facts  and  arguments  adduced  by  me  in  a  paper  entitled  "The 
relations  of  the  mineral  belts  of  the  Pacific  Slope  to  the  great  upheavals"  (Am.  Jour.  Sei.,  lid  scries, 
vol.  28,  1884,  p.  209)  and  iu  Statistics  and  Technology  of  the  Precious  Metals,  by  S.  F.  Einmous  arid 
G.  F.  Becker,  Tenth  Census  Repts.  U.  S.,  vol.  13,  Chapter  I.  The  present  chapter  also  contains  much 
that  is  new. 

176 


FORMATIONS  IN  CALIFORNIA.  177 

ance  which  .added  an  important  portion  of  the  auriferous  slates  to  the 
Sierra  Nevada.  The  Coast  Ranges  belong  to  the  same  mountain  system 
as  the  Sierra  Nevada.  The  upheaval  mentioned  was  accompanied  or  fol- 
lowed by  intense  metamorphism,  the  only  event  of  the  kind  known  to  have 
occurred  in  the  history  of  the  Coast  Ranges.  A  great  non-conformity 
exists  between  the  metamorphic  rocks  and  the  overlying  late  Cretaceous 
strata.  The  Tojon  formation  is  shown  to  be  Eocene,  as  it  was  regarded 
by  Conrad,  and  it  is  here  shown  to  be  absolutely  continuous  with  the 
Upper  Cretaceous  The  ore  deposits  have  an  intimate  structural  connec- 
tion with  the  system  of  fissures  along  which  the  upheaval  of  the  ranges 
took  place.  So,  also,  has  the  distribution  of  volcanic  rocks,  the  earliest  of 
which  probably  date  from  the  Pliocene.  The  ore  deposits  appear  to  be 
contemporaneous  with  and  later  than  the  eruptions  and  have  a  more  or 
less  intimate  chemical  relation  to  them. 

Formations  found  in  California. — The  reader  may  perhaps  be  glad  to  be  reminded 
of  the  formations  which  have  hitherto  been  recognized  in  California  It  is' 
not  absolutely  certain  that  the  Archrean  occurs  in  this  State,  but,  as  I 
pointed  out  some  years  .since,  the  unquestionable  occurrence  of  the  Ar- 
chaean in  Arizona,  together  with  the  similarity  of  the  rocks  of  southeastern 
California  to  those  of  the  adjoining  territory,  makes  it  highly  probable  that 
San  Bernardino  County  is  largely  Archaean.1  If  so,  this  formation  may 
enter  into  the  composition  of  the  southern  Sierra.  The  geologists  of  the 
fortieth  parallel  exploration  also  found  the  Archaean  in  central  Nevada  in 
its  normal  relation  to  the  Paleozoic  and  determined  areas  close  up  to  the 
California  line  in  this  latitude  as  Archajan.  Their  investigations  did  not 
extend  into  California,  but  they  showed  that  during  the  Paleozoic  a  conti- 
nental area  existed  west  of  longitude  117°  30',  latitude  40°,  and  it  appears 
certain  that  this  area  must  have  embraced  at  least  a  portion  of  the  great 
Sierra,  which  is  thus  probably  composed  to  a  considerable  extent  of  Ar- 
cliEean  schists.  The  Carboniferous  was  first  recognized  by  Dr.  Trask  in 
1834'-'  on  the  McCloud  River.  Professor  Whitney's  party  found  it  near 

1  Tenth  Census  Kepts.  U.  S.,  vol.  13,  p.  47. 

a  Report  on  the  Geology  of  the  Coast  Mountains  etc.,  by  Dr.  John  B.  Trask,  Senate  [of  California] 
Doc,  No.  1.4,  1835,  p.  50. 

MON  XIII 12 


178  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Pence's*  ranch,  in  Butto  County,  and  inferred  from  similarity  of  position 
and  lithological  character  that  other  rocks  on  the  western  flank  of  the 
Sierra  may  also  be  of  this  age.  No  Carboniferous  fossils  are  known  to 
occur  in  the  Coast  Ranges. 

Fossiliferous  beds  were  found  by  Professor  Whitney's  party  at  Genes- 
see  Valley,  in  Plumas  County,  which  Mr.  Meek  determined  as  Triassic. 
The  material  upon  which  this  determination  rests  appears,  however,  to  be 
somewhat  meager  and  unsatisfactory.  A  similar  fauna  has  been  found  at 
a  few  points  in  Nevada,1  but  not  elsewhere  in  California.  Near  the  south- 
ern end  of  the  gold  belt  of  California  fossils  were  found  on  the  Mariposa 
estate  in  1 864 3  They  were  figured  and  described  by  Meek.3  The  mosi 
important  shell  he  determined  as  AuceUa  Erringtonii,  the  specific  name  being 
given  in  honor  of  a  resident  who  drew  attention  to  the  occurrence  of  the 
fossil.  Meek  observes : 4 

As  tbis  genus  is,  so  far  as  kuown,  entirely  confined  to  the  Jurassic  rocks,  while 
an  Amw&ium  like  shell  from  the  same  slates  is  closely  allied  to  a  Jurassic  species,  and 
the  genus  Belemnites  is  not  generally  regarded  as  dating  back  beyond  the  commence 
ment  of  the  Jurassic  period,  I  can  scarcely  entertain  a  doubt  that  these  gold-bearing 
slates  really  belong  to  that  epoch,  and  probably  to  some  of  its  lower  members,  at  whic^i 
horizon  most  of  the  known  European  species  of  AuceUa  are  said  to  occur. 

The  same  species  of  Amelia  was  found  by  Professor  Whitney's  party, 
after  the  publication  of  Meek's  determination,  at  a  number  of  localities  on 
the  gold  belt,  and  ammonites  were  also  discovered.  It  will  be  observed 
that  Meek  laid  the  chief  weight  in  his  determination  of  the  age  of  these 
beds  on  the  occurrence  of  AuceUa. 

Previous  to  the  discovery  of  the  fossil  fauna  of  the  Mariposa  estate 
fossils  had  been  found  at  many  points  on  the  Coast  Ranges  and  along  the 
foot-hills  of  the  Sierra,  which  were  described  by  Mr.  Gabb  as  Cretaceous.5 
Many  more  were  added  later,  and  Mr.  Gabb  ultimately  divided  the  Creta- 
ceous of  California  into  the  Shasta,  Chico,  Martinez,  and  Tejon  groups,  the 
last  being  the  highest. 

'King:  U.  S.  Geol.  Kxpl.  40th  Parallel,  vol.  1,  Systematic  Geology. 

"The  houor  of  the  first  discovery  of  these  fossils  was  somewhat  warmly  contested.  See  Whitney's 
Auriferous  Gravels  aud  Proc.  California  Acad.  Nat.  Sci.;  also,  Mr.  Clarence  King's  Mountaineering  in 
l  he  Sierras. 

3  Geol.  Survey  California,  Geology,  vol.  1,  p.  477. 

<Ibid.,  p.  478. 

5  Geol.  Survey  Ca!ifi>nin.  P.il.ooutolo^y,  vol.  I, 


GABB'S  DIVISIONS.  179 

The  following  paragraphs,  copied  from  Professor  Whitney's  preface  to 
Greol.  Survey  California,  Palaeontology,  vol.  2,  pages  xiii  and  xiv,  give  a 
concise  account  of  these  formations  in  accordance  with  Mr.  Gabb's  later 
views  and  as  they  were  finally  adopted  by  the  State  survey: 

(1)  TheTi'jon  group,  the  most  modern  member,  the  Division  B  of  Paleontology, 
Vol.  I,  is  peculiar  to  California.    It  is  found  most  extensively  developed  in  the  vicinity 
of  Fort  Tejon  and  about  Martinez.     From  the  latter  locality  it  forms  an  almost  con- 
tinuous belt  in  tbe  Coast  Ranges  to  Marsh's,  15  miles  east  of  Monte  Diablo,  where  it 
sinks  under  the  San  Jonquin  plain.    It  was  also  discovered  by  the  different  members  of 
the  survey  at  various  points  on  the  eastern  face  of  the  same  range  as  far  south  as  New 
Idria,  and,  in  the  summer  of  1S6G,  by  Mr.  Gabb,  in  Mendocino  County,  near  Hound 
Valley,  the  latter  locality  being  the  most  northern  point  at  which  it  is  as  yet  known. 
It  is  the  only  coal-producing  formation  in  California. 

This  group  contains  a  large  and  highly  characteristic  series  of  fossils,  the  larger 
part  peculiar  to  itself,  while  a  considerable  percentage  is  found  extending  below  into 
the  next  group,  and  several  species  still  further  down  into  the  Chico  group.  Mr. 
Gabb  considers  it  as  the  probable  equivalent  of  the  Maestricht  beds  of  Europe. 

(2)  The  Martinez  group  is  proposed  provisionally,  to  include  a  series  of  beds  ot' 
small  geographical  extent  found  at  Martinez  and  on  the  northern  flank  of  Monte 
Diablo.     It  may  eventually  prove  to  be  worthy  of  ranking  only  as  a  subdivision  of 
the  Chico  group. 

(3)  The  Chico  group  is  one  of  the  most  extensive  and  important  members  of  the 
Pacific  Coast  Cretaceous.     Its  exact  relations  with  the  formation  in  Europe  have  not  yet 
been  fully  determined,  though  it  is  on  the  horizon  of  either  the  Upper  or  Lower  Chalk, 
and  may  probably  prove  to  be  the  equivalent  of  both.     It  is  extensively  represented 
in  Shasta  and  Butte  Counties  and  in  the  foot-hills  of  the  Sierra  Nevada  as  far  south  as 
Folsorn,  occurring  also  on  the  eastern  face  of  the  Coast  Ranges  bordering  the  Sacra- 
mento Valley  at  Martinez,  and  again  in  Oristimba  Canon,  in  Stanislaus  County.    It 
includes  all  of  the  known  Cretaceous  of  Oregon  and  of  the  extreme  northern  portion 
of  California,  and  is  the  coal-bearing  formation  of  Vancouver's  Island. 

(4)  The  Sh  ista  group  is  a  provisional  name,  proposed  to  include  a  series  of  beds 
of  different  ages,  but  which,  from  our  imperfect  knowledge  of  the  subject,  cannot  yet 
be  separated;  it  includes  all  below  the  Chico  group.     It  contains  fossils,  seemingly 
representing  ages  from  the  Gault  to  the  Neocomian  inclusive,  and  is  found  principally 
in  the  mountains  west  and  northwest  of  the  Sacramento  Valley.    Two  or  three  of  its 
characteristic  fossils  have  been  found  in  the  vicinity  of  Monte  Diablo,  and  one  of  the 
same  species  has  been  sent  from  Washington  Territory,  east  of  Puget  Sound.     Few 
or  none  of  its  fossils  are  known  to  extend  upwards  into  the  Chico  group.1 

To  these  I  have  added  another  series  of  Cretaceous  strata  lying  above 
the  Shasta,   and,   according   to  the  paleontological  evidence,   below  the 

1  Mr.  Gabb's  work  on  tlio  fossils  of  California  is  mainly  contained  in  Geol.  Survey  California,  Pa- 
lieotitology,  vols.  1  and  ••>;  but  the  following  papers  may  be  referred  to  for  other  discussions  which  relate  to 
his  work  in  that  State:  Am.  Jonr.  Conchol.,  vol.  2,  pp.  87-92;  ibid.,  vol.  5,  pp.  5-18;  Am.  Jour.  Sci..2d 
sorirs,  vol.  11, 1-W,  pp.  220-339  ;  Proc.  California  Acad.  Nat.  Sci.,  vol.  3,  pp.  301-306;  ibid.,  vol. .'.,  pp.  7-8. 


180  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Chico.  This  will  be  called  the  Wallala  series.  Above  the  Tejou  is  found 
unquestionable  Miocene,  and  resting  unconforinably  upon  the  Miocene  the 
Pliocene  is  met  with  in  a  few  localities.  To  the  Pliocene  also  belong  the 
fresh-water  beds  of  Cache  Lake,  which  will  be  described  later  in  this  chap- 
ter. Between  these  last  eras  occurred  an  important  upheaval  recognized 
by  Professor  Whitney,  and  to  which  ho  ascribed  the  formation  of  the 
Coast  Ranges,  while  a  great  uplift  of  the  Sierra  and  of  the  Basin  ranges 
lie  attributed,  in  accordance  with  the  evidence  before  him,  to  a  Post-Juras- 
sic upheaval. 

Nomenclature  here  adopted. —  To  facilitate  reference  to  the  various  groups  of 
strata  Dr.  White  and  I  have  agreed  to  give  local  names  to  several  of  the 
California  occurrences.  The  fossiliferous  beds  of  the  Mariposa  estate  will 
be  known  as  the  Mariposa  beds;  the  groups  especially  characterized  by 
the  presence  of  Aucella  in  the  Coast  Ranges  will  be  referred  to  as  the 
Knoxville  series,  because  they  are  typically  developed  and  have  been  spe- 
cially studied  in  the  neighborhood  of  the  mining  town  of  that  name;  the 
rocks  from  which  Messrs.  Gabb  and  Whitney  obtained  a  large  fauna,  con- 
sidered by  them  as  probably  equivalent  to  the  Gault,  will  ba  called  the 
Horsetown  beds;  and  a  series  which  occurs  along  the  coast  north  of  the 
Russian  River  will  be  denominated  the  Wallala  beds.  Meek's  Jurassic  on 
the  western  slope  of  tin  Sierra  Nevada  is  thus  equivalent  to  the  Mariposa 
beds.  The  Shasta  group  of  Messrs.  Gabb  and  Whitney  is  here  divided 
into  two  series,  recognized  by  them  as  distinct,  the  Knoxvillo  and  tho 
Horsetown.  The  designations  Chico  and  Tejon  are  retained,  but  the  latter 
is  considered  Eocene.  The  Martinez  is  regarded  as  a  portion  of  the  Chico 
series. 

G.-anite. — As  has  been  shown  in  the  preceding  chapters,  there  is  much 
evidence  that  granite  underlies  the  entire  quicksilver  belt,  and  indeed  the 
whole  of  central  California.  South  of  San  Francisco  it  is  frequently 
exposed  in  positions  where  erosion  has  been  greatest,  viz,  along  the  axial 
lines  of  ranges  and  at  the  sea-coast;  it  is  also  exposed  at  a  few  points 
somewhat  north  of  San  Francisco,  on  the  coast;  and  the  Farallone  Islands, 
20  miles  off  the  Golden  Gate,  are  granite.  To  the  north  of  the  Bay 
of  San  Francisco,  away  from  the  coast,  granite  is  not  known  to  occur  in 


AX01KNT  HOCKS.  181 

place  for  about  one  hundred  and  twenty-five  miles,  but  this  is  probably 
for  want  of  exploration,  since  in  some  parts  of  Cache  Creek,  for  example, 
granite  predominates  among  the  stream  pebbles.1  According  to  Professor 
Whitney2  the  highest  portions  of  the— T-rinity  or  Shasta  Mountains  are 
granite.  The  "Wallala  beds,  too,  though  far  from  any  known  outcrop  of 
granite,  are  in  large  part  granitic  conglomerates  and  the  sandstones  of  the 
entire  quicksilver  belt  are  arcose.  I  have  nowhere  met  granites  along  the 
quicksilver  belt  which  appeared  to  me  to  be  intrusive. 

Gaviian  limestone— In  the  Gavilaii  Range,  some  sixty  miles  south  of  the 
Bay  of  San  Francisco,  the  lowest  sedimentary  formation  encountered  is  in 
part  limestone,  which  at  the  points  examined  is  extraordinarily  crystalline, 
oftentimes  consisting  of  a  loosely  adherent  mass  of  imperfect  calcite  crys- 
tals. Associated  with  it  are  rocks  of  the  Archaean  gneiss  type.  This 
occurrence  has  been  very  little  investigated  and  nothing  further  is  known 
of  its  age.  It  is  possible  that  it  is  a  member  of  the  Knoxville  series  much 
more  metamorphosed  than  usual,  but  it  appears  to  me  more  probable 
that  it  is  a  remnant  of  some  older  formation  which  has  perhaps  under- 
gone repeated  metamorphism.  For  the  purposes  of  this  memoir  an  exact 
determination  of  its  character  is  not  important. 

Before  passing  to  a  general  characterization  of  the  Knoxville  beds, 
which  will  be  found  to  be  the  most  important  and  most  interesting  in  the 
State  of  California,  it  seems  best  to  present  the  somewhat  complex  evi- 
dence obtained  as  to  the  distribution  and  affiliations  of  this  series;  indeed, 
it  appears  hardly  practicable  to  describe  it  without  discussing  its  chemical 
and  structural  relations,  unless  the  results  which  I  have  reached  as  to  these 
are  taken  for  granted. 

Metamorphism  in  the  Coast  Ranges. Tlll'OUgllOUt   tllC   Coast   RaUgCS  of  California 

there  occur  large,  irregular  areas  in  a  somewhat  peculiar  condition  of  meta- 
morphism, which  has  been  discussed  in  a  preceding  chapter.  Its  prominent 
macroscopical  characteristics  are  the  predominance  of  recrystallization,  ser- 
pentinization,  and  silicification. 

1  A  very  large  part  of  the  country  in  this  nci<rhl>orluM»l  is  covered  with  thickets  (chaparral)  which 
are  practically  impenetrable. 

sGeol.  Survey  California,  Geology,  vol.  1,  p.  l!j:i. 


182  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  dynamical  action  which  accompanied  or  preceded  this  metamor- 
phisrn  was  of  a  very  violent  character,  so  that  in  the  greater  proportion  of 
cases  it  is  a  manifest  impossibility  to  construct  sections  of  the  metamorphic 
areas,  no  stratum  being1  continuous  for  more  than  a  few  feet,  Sharp  con- 
tortion and  plication  are  also  common,  but  where  they  occur  it  is  usually 
apparent  that  the  flexures  have  been  accomplished  not  in  the  main  by  plas- 
tic deformation,  but  by  comminution  of  the  entire  mass,  the  residual  frag- 
ments often  averaging  less  than  a  quarter  of  an  inch  in  diameter.  In  the 
accompanying  distortion  these  particles  have  retained  approximately  their 
original  relative  positions  and  have  subsequently  been  recemented,  chiefly 
by  silica.  The  minute,  polyhedral  rock  fragments,  however,  have  under- 
gone no  visible  distortion.  These  occurrences  coincide  in  a  remarkable 
manner  with  the  results  of  Mr.  Daubree's  experiments  on  the  fracture  of 
various  substances  by  torsion  and  pressure.1  As  is  shown  in  Chapter  III, 
this  probably  indicates  that,  at  the  time  of  upheaval,  these  strata  were 
buried  at  a  depth  of  not  more  than  a  few  thousand  feet  below  the  surface 

The  most  striking  instances  of  such  fracturing  are  met  with  among 
thin-bedded  rocks,  either  sandstones  or  sandy  shales,  and  such  are  remark- 
ably frequent  in  this  series ;  indeed,  they  might  be  said  to  bo  characteristic 
of  it.2  They  are  occasionally  met  with  in  other  formations,  and  it  would 
be  strange  indeed  if  the  conditions  favorable  to  thin  bedding  had  prevailed 
along  the  Coast  Ranges  only  during  a  single  era.  As  a  rule,  however,  the 
rocks  which  vest  upon  the  metamorphic  series  are  thick-bedded,  rather  coarse 
and  uniform  sandstones. 

Besides  this  series  of  metamorphic  rocks  there  are  others  of  different 
age  in  the  Coast  Ranges  to  which  the  term  metamorphic  might  not  improp- 
erly be  applied.  These  will  be  described  a  little  later. 

Age  of  the  principal  m2tamorphic  rocks. With  the  possible   CXCCptlOU    of    tllC    limO- 

stone  mentioned  above,  this  metamorphic  series  is  stratigraphically  the 
lowest  in  the  Coast  Ranges  and  appears  to  rest  upon  the  granite.  It  forms 
the  crests  of  many  mountain  ranges  and  occupies  the  whole  surface  in  some 
of  the  more  mountainous  regions.  Detailed  studies  of  the  structure  show 

1  Bull.  Soc.  ge'ologique  France,  3d  series,  vol.  7,  1878-79,  p.  108. 

-The  peculiarity  of  those  thin-bedded,  plicated,  metamorphic  rocks  was  observed   by  Professor 
Whitney. 


AGE  OF  THE  METAMOKI'IIICS.  183 

that  as  a  rule  the  hills  of  metamorphic  rock  are  synclinal,1  and  consequently 
they  must  have  undergone  great  erosion.  The  elevations  of  later  age  do 
not  exhibit  this  peculiarity. 

Rocks  of  the  metamorphic  series  often-  pass  over  into  unaltered  beds  in 
the  Coast  Ranges  under  such  circumstances  as  to  leave  no  doubt  that  they 
are  of  the  same  age ;  but  unfortunately  the  unchanged  strata  seldom  con- 
tain determinable  fossils  and  only  a  small  number  of  occurrences  is  known 
in  which  the  age  can  be  satisfactorily  established  by  direct  evidence.  In 
addition  to  these  cases,  however,  there  is  a  considerable  amount  of  tolera- 
bly satisfactory  indirect  evidence  available,  when  all  the  circumstances  are 
taken  into  consideration.  The  neighborhood  of  Knoxville  affords  an  ex- 
cellent opportunity  for  the  study  of  the  metamorphic  rocks.  The  section 
across  the  north  fork  of  Davis  Creek,  a  little  north  of  the  Reed  mine,  a  short 
distance  from  Knoxville,  shows  that  the  ravine  occupies  an  eroded  anticli- 
nal, of  which  the  western  portion  is  highly  metamorphic,  while  the  eastern 
consists  in  part  of  highly  fossiliferous  strata  containing  Aucella  of  two 
varieties,  with  other  molluscan  remains  characteristic  of  the  horizon  which 
in  this  memoir  is  called  the  Knoxville  series.  The  geological  map  of  the 
district  shows  that  the  strike  of  the  unaltered  strata  throughout  is  tolerably 
constant,  but  that  areas  of  metamorphic  and  unaltered  rocks,  the  latter 
nearly  all  containing  a  few  fossils,  are  interspersed  in  the  most  irregular 
manner.  While  the  passage  from  metamorphosed  to  fresh  rock  is  usually 
rather  sudden,  there  are  also  clear  cases  of  transition.  The.  whole  structure 
and  the  stratigraphical  relations  are  such  as  to  preclude  every  hypothesis 
except  one,  viz,  that  the  metamorphic  rock  is  an  alteration  product  of  the 
same  beds  which  contain  Aucella  and  the  accompanying  fossils. 

Close  to  the  Manzanita  gold  and  quicksilver  mine  on  Sulphur  Creek, 
in  Colusa  County,  the  metamorphic  rocks  contain  impressions  of  Aucella 
I'/orJiii,  and  close  by  are  beds  of  limestone  full  of  Rhynckohetta  Wliilneyi? 
The  metamorphic  rocks  of  this  region  are  serpentinized  and  silicified,  and 

'Also  observed  by  Professor  Whitney :  The  Auriferous  Gravels,  Mom.  Mus.  Comp.  Zool.  Harvard 
Coll.,  vol.  0,  No.  1,  1880,  chai>.  1. 

2  These  specimens  were  determine.l  by  direct  comparison  with  spscimeu.s  iu  the  collection  of  the 
State  survey.  The  figure  given  in  Oool.  Survey  California,  Palirontolojjy,  vol.  2,  PI.  XXXIV,  is  incorrect 
in  important  particulars. 


184  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  thin-bedded  strata  show  the  characteristic  contortions  accompanied  by 
a  fine  net-work  of  veins  of  silica.  At  Mt.  Diablo,  too,  there  is  abundant 
proof  of  the  Knoxville  age  of  the  metamorphio  rock.  Professor  Whitney, 
writing  before  Mr.  W.  M.  Gabb  had  made  his  final  divisions  of  the  California 
Cretaceous,  mentions  the  occurrences  at  Mt.  Diablo  as  conclusive  of  the 
Cretaceous  age  of  the  metamorphic  rocks,  but  without  enumerating  the 
.associated  fossils.  From  an  examination  of  the  fossil  localities  in  Mr. 
Gabb's  work,  however,  it  appears  certain  that  these  were  Aucella  etc.  An 
examination  which  Dr.  White  and  I  undertook  for  the  purpose  shows  that 
in  Bagley  Creek,  about  a  mile  from  the  summit,  Aucella  occurs  abundantly 
close  to  the  edge  of  the  metamorphosed  area  —  indeed,  in  partially  meta- 
morphosed strata  conformable  with  those  extremely  altered  and  in  struct- 
ural relations  to  them  which  very  clearly  indicated  the  same  age.  Mr.  Tur- 
ner subsequently  found  a  series  of  beds,  some  of  which  had  escaped  trans- 
formation and  contained  Aucella,  though  inclosed  on  botli  sides  by  highly 
metamorphic  strata.  At  .ZEtna  Springs,  in  Napa  County,  near  the  ^Etna  and 
Napa  consolidated  quicksilver  mines,  Aucella  also  occurs  in  the  same  un- 
mistakable relation  to  the  metamorphic  rocks.  In  the  examinations  described 
in  this  volume,  Aucella  has  been  detected  in  immediate  connection  witli  the 
metamorphic  beds  near  the  St.  John's  mine,  Solano  Coiinty,  and  in  the  Santa 
Lucia  Range,  near  San  Luis  Obispo.  Mr.  Gabb  further  mentions  an  Aucella 
locality  below  the  New  Almaden  mines.  I  have  not  succeeded  in  finding 
Ancdla  in  this  region,  which,  however,  in  the  neighborhood  of  the  area  sur- 
veyed, shows  only  metamorphic  rocks  exactly  similar  to  those  of  Mt.  Diablo 
and  Knoxville,  Miocene  rocks  lying  unconformably  upon  the  metamorphics 
and  volcanics.  It  appears  substantially  certain  therefore  that  the  Aucella- 
bearing  beds  which  Mr.  Gabb  detected  must  have  belonged  to  the  meta- 
morphic series.  The  age  of  the  metamorphic  rocks  is  thus  determined  at 
a  considerable  number  of  points  scattered  along  the  Coast  Ranges  for  a  dis- 
tance of  300  miles,  or  nearly  three-quarters  of  the  entire  length  of  the  Coast 
Range  system  of  mountains.  Alcatraz  Island,  close  to  San  Francisco,  consists 
of  metamorphic  sandstone  and  shales  not  distinguishable  from  those  of  San 
Francisco  -or  of  Mt.  Diablo.  Here  Major  Elliot  discovered  an  Inoccramus 
not  known  to  occur  elsewhere,  considered  by  Mr.  Gabb  and  Dr.  White  as 


TEUTIA1MES.  185 

establishing  the  Cretaceous  age  of  these  rocks,  though  indecisive  of  the 
portion  of  this  formation  to  which  they  should  be  referred.  The  above 
comprise  all  the  instances  definitely  known  in  which  the  age  of  the  silicified 
and  serpentinized  metamorphic  rocks  is-4i*ectly  determinable  by  paleonto- 
logical  evidence.  Mr.  Gabb  also  found  Aucdla  along  Puta  Creek,  Lake 
County.  This  stream  runs  through  a  region  chiefly  occupied  by  highly 
metamorphosed  rocks,  and,  were  the  exact  locality  known,  it  would  probably 
furnish  another  instance  of  transition. 

Besides  the  rocks  referred  to  above,  the  Coast  Ranges  include  others 
which  have  been  subjected  to  more  or  less  complete  alteration.  Thus, 
along  the  shore  of  Carmelo  Bay,  Miocene  schists  have  been  locally  changed 
to  a  cindery  mass,  as  if  by  the  action  of  heat  ;  but  these  rocks  bear  no 
resemblance  to  the  serpentinized  and  silicified  material  just  described. 
More  or  less  complete  induration  is  common,  even  in  the  most  recent  rocks 
of  the  coast,  and  oxidation  and  impregnations  with  calcite  and  gypsum 
occur  abundantly  in  rocks  of  all  ages.  In  the  Arroyo  de  la  Penitencia, 
above  Alum  Rock,  near  San  Jose,  there  is  also  an  area  of  altered  Miocene 
sandstones  referred  to  by  Professor  Whitney.1  The  rock  here  is  much 
indurated  and  is  full  of  veins  of  calcite.  No  objection  can  be  made  to  its 
description  as  metamorphic  by  Professor  Whitney  ;  but  it  is  not  serpentin- 
ized and  silicified  and  does  not  partake  of  the  characteristics  so  strongly 
marked  in  the  highly  metamorphosed  rocks  of  the  Knoxville  group.  On 
the  other  hand,  there  are  plenty  of  rocks  of  this  group  no  more  altered  than 
the  Miocene  of  the  Arroyo  de  la  Penitencia  and  some  areas  still  less  modi- 
fied. The  Tertiary  of  the  Arroyo  has  been  subjected  to  influences  seem- 
ingly identical  with  those  which  have  affected  portions  of  the  Knoxville 
beds,  but  not  to  those  which  have  produced  in  the  older  strata  the  charac- 
teristic serpentinization  and  silicification. 

Professor  Whitney  also  refers  twice2  to  altered  beds  in  the  San  Fran- 
cisquito  Pass,  which,  indeed,  is  to  the  south  of  the  Coast  Ranges  as  usually 
defined.  In  the  first  reference  he  states  that  "this  belt  of  metamorpliic  is 
referred  by  us  to  the  Cretaceous  formation  from  general  analogy  rather 

1  Geol.  Survey  California,  Geology,  vol.  1,  p.  51. 

•Ibid.,  p.  1'Jo;  The  Auriforous  Gravels:  Mein.  Mus.  Comp.  Zool.  Harvard  Coll.,  vol.  f>,  No.  1,  1880i 


.  IP. 


186  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOl'K. 

than  from  .any  direct  evidence  of  fossils:'  In  the  second  reference  they  are 
mentioned  as  "  Miocene  rocks  turned  up  on  edge  and  in  places  so  much  meta- 
morphosed as  to  be  converted  into  mica-slate."  No  statement  of  the  means 
of  determination  of  the  age  of  these  beds  accompanies  this  remark,  which, 
however,  occurs  in  a  brief  summary  of  the  geology  of  the  Coast  Ranges. 
Whatever  the  evidence  may  be  upon  which  the  change  of  reference  was 
made  it  can  have  little  bearing  upon  the  age  of  the  metamorphics  in  the 
central  Coast  Ranges,  nor  is  serpentinization  referred  to  as  forming  a  part 
of  the  phenomena. 

So  far  as  is  known,  therefore,  no  beds  in  the  Coast  .Ranges  of  California 
younger  than  the  Knoxville  group  have  experienced  the  peculiar  magnesian 
and  siliceous  metamorphism  so  characteristic  of  these  ranges.  This  fact 
raises  a  presumption  that  the  metamorphism  was  effected  prior  to  the  depo- 
sition of  the  rock  resting  upon  the  metamorphic  series,  and  this  presumption 
is  confirmed  by  examination  of  the  conglomerates  of  the  later  rocks.  There 
rest  upon  the  metamorphic  series  at  different  localities  Wallala  beds,  which 
Dr.  White  regards  as  middle  Cretaceous;  Chico  beds,  representing  the  very 
close  of  the  Cretaceous;  and  Miocene  strata.  The  fossils  of  the  Wallala 
series  were  found  in  a  conglomerate  consisting  largely  of  serpentine  pebbles, 
accompanied  by  siliceous,  metamorphic  rocks  exactly  similar  to  those  accom- 
panying the  serpentine  in  the  altered  rocks  of  the  Knoxville  series.  At  New 
Idria  there  is  a  bed  of  conglomerate  associated  with  Chico  fossils  near  an 
extensive  metamorphic  area.  The  pebbles  are  mainly  siliceous,  as,  indeed, 
is  usually  the  case  in  conglomerates  derived  from  the  metamorphic  rock, 
for  the  simple  reason  that  serpentine  is  both  easily  decomposed  and  easily 
abraded.  Careful  search,  however,  revealed  pebbles  in  this  conglomerate 
which  consisted  in  part  of  serpentine,  a  result  confirmed  by  microscopical 
examination.  The  Miocene,  too,  for  instance  at  Ne\v  Almaden,  contains 
abundant  pebbles  manifestly  derived  from  the  surrounding  metamorphic  rock. 

No  fossils  older  than  the  Knoxville  group  are  known  to  occur  in  the 
Coast  Ranges  and  no  known  fact  suggests  the  existence  of  older  rocks, 
excepting  the  character  of  the  limestone  and  gneisscid  rocks  of  the  Gavilan 
Range  already  mentioned,  for  the  habitus  of  the  peculiar  metamorphic 
rocks  under  discussion  is  remarkably  uniform. 


KKAS  OF  METAMOKM'IUSM.  187 

Similarity  of  lithological  and  physical  character  may,  I  think,  be 
given  too  much  weight  in  geological  diagnosis.  I  cannot  conceive,  for 
example,  that  any  degree  of  similarity  between  the  rocks  of  California  and 
those  of  Switzerland  should  properly  -he- considered  as  even  tending  to 
prove  the  age  of  either.1  I  go  further,  and  refuse  to  regard  the  metamor- 
phism  of  the  rocks  of  liutte  County  as  necessarily  contemporaneous  with 
that  of  the  strata  of  Napa  County,  in  spite  of  external  similarity.  On  the 
other  hand,  within  properly  limited  areas,  observations  show  that  the  same 
fauna  is  associated  with  similar  rocks;  while,  if  it  were  impracticable  to 
draw  any  conclusions  as  to  age  except  where  the  rock  is  fossiliferous  or 
where  absolute  continuity  with  fossiliferous  localities  uninterrupted  by 
faults  could  be  proved,  geological  mapping  would  be  impossible.  In  Cali- 
fornia great  use  can  be  made  of  resemblances.  Thus  the  Tejon  strata  of 
New  Idria  are  mostly  heavy-bedded  sandstones  of  a  peculiarly  light  color, 
which  there  distinguishes  them  from  the  tawny  Chico  sandstones.  Both 
are  fossiliferous  there,  as  also  near  Mt.  Diablo,  where,  at  a  distance  of  125 
miles  from  New  Idria,  they  preserve  the  same  external  characteristics. 
Similarly,  the  Knoxville  beds  of  Knoxville  and  Mt.  Diablo  are  externally 
indistinguishable,  and  in  their  typical  development,  even  when  unaltered, 
very  different  from  most  of  the  later  rocks. 

Strata  older  than  the  Knoxville  period  may  nevertheless  be  included 
in  the  metamorphie  series  and  may  have  undergone  upheaval  and  meta- 
morphism  at  the  same  date.  There  is  also  a  possibility  that  older  rocks  not 
only  exist,  but  were  metamorphosed  before  the  deposition  of  the  Knoxville, 
so  that  the  metamorphie  areas  in  contact  with  the  Wallala  beds  on  the  coast 
and  with  the  Chico  strata  at  New  Idria  may  conceivably  be  earlier  than 
the  Knoxville.  Even  this  hypothesis,  which,  in  the  absence  of  any  evi- 
dence tending  to  establish  it,  seems  rather  strained,  would  have  no  effect 
on  the  principal  conclusions  drawn  in  this  chapter,  unless  it  could  also  be 

1  The  resemblance  between  the  Miocene  sandstones  and  the  Molasse  of  Switzerland  was  advanced 
by  Mr.  Jules  Marcou  floe,  cit.)  as  an  evidence  of  the  Tertiary  age  of  the  California  rocks.  That  the 
resemblance  exists  I  can  testify  from  observation.  To  me  it  indicates  only  that  the  California  Miocene 
and  the  Molasse  were  both  deposited  near  the  shore  of  land  areas  largely  composed  of  Archaean  rocks. 
Mr.  Marcou  attributes  to  ignorance  of  lithology  my  failure  to  appreciate  it  as  au  indication  of  age,  and 
he  regrets  that  "  a  competent  person  has  not  been  selected  for  the  study  of  the  Tertiaries  of  Califor- 
nia" (American  Geological  Classilication  and  Nomenclature,  1888,  p.  52).  I  am  very  sorry  that  my 
work  produces  so  bad  au  impression  on  Ibis  veteran  geologist. 


188  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

maintained  that  the  violent  upheaval  and  metainorphism  which  followed 
the  Knoxvillo  left  the  supposed  older  areas  undisturbed.  This  would  con- 
flict with  all  analogy. 

The  foregoing  facts  and  the  necessary  inferences  from  them  appear  to 
justify  the  statement  that  the  silicified  and  serpentinized  metamorphic  rocks 
of  the  Coast  Ranges  include  a  portion  of  the  Knoxville  beds,  and  do  not 
include  any  portion  either  of  the  Chico  or  of  the  Wallala  series,  while  if 
there  were  pre-Knoxville  rocks  within  the  metamorphic  areas  they  must 
have  undergone  at  least  a  fresh  disturbance  at  the  time  when  the  Knoxville 
beds  were  broken  up  and  metamorphosed. 

Non  conformity  between  the  Knoxville  beds  and  the  Chico. Had    tllC    pl'OOf   of    tlllS    nOll- 

conformity  been  a  simple  matter,  it  could  not  have  escaped  the  attention  of 
some  one  of  the  able  geologists  who  have  worked  in  the  Coast  Ranges. 
The  difficulty  is  in  part  due  to  the  rarity  of  fossils  in  the  older  groups  over 
a  great  portion  of  the  area  in  question,  which  often  leaves  the  observer 
without  absolute  proof  of  the  age  of  the  rocks  about  him;  but  complexity 
of  structure  is  the  main  obstacle.  Few  geological  phenomena  are  more 
striking  than  a  non-conformity  where  the  overlying  strata  are  nearly  hori- 
zontal, the  underlying  rocks  greatly  inclined,  and  the  exposure  tolerable. 
This  combination  is  rare  in  the  Coast  Ranges,  and  no  such  case  is  known 
where  the  Shasta  and  Chico  beds  meet.  The  Post-Miocene  uplift  traced 
by  Professor  Whitney  has  folded,  faulted,  and  broken  the  later  Cretaceous 
and  the  Tertiary  rocks,  as  well  as  the  earlier  strata  upon  which  these  were 
unconformably  deposited;  so  that  it  is  usually  far  from  easy  to  make  out 
the  effects  due  to  the  earlier  and  later  disturbances,  respectively,  and  still 
more  difficult  to  prove  that  no  explanation  except  that  of  a  non-conformity 
beneath  the  Chico  will  account  for  the  facts.  I  believe  that  the  structural 
evidence  to  be  presented  clearly  establishes  this  non-conformity,  but  the 
proof,  though  convincing,  is  less  abundant  than  could  be  wished.  The 
evidence  will  first  be  presented  from  a  purely  structural  point  of  view  and 
will  then  be  re-enforced  by  an  independent,  paleontological  argument. 

In  the  neighborhood  of  the  New  Idria  mine  the  metamorphic  rocks 
have  been  greatly  disturbed,  while  the  Chico  strata,  though  tilted  at  a  high 
angle,  are  remarkably  regular.  Owing  to  the  steepness  of  the  contact,  how- 


NON-CONFORMITY  BELOW  THE  CHICO.  189 

ever,  no  exposures  showing  both  series  together  could  be  found  from  which 
thoroughly  satisfactory  inferences  could  be  drawn  as  to  the  relations  of  the 
underlying  and  overlying  rocks.  I  therefore  resorted  to  a  study  of  the 
exposures  of  each  separately,  for  which  the  region  offers  unusual  facilities. 
It  was  found  possible  to  follow  single  strata  of  the  Chico  uninterruptedly 
for  the  greater  part  of  a  mile,  and,  by  the  aid  of  lithological  peculiarities, 
combined  with  topographical  indications  and  the  strikes  observed  at  the 
exposures,  to  recover  the  croppings  with  substantial  certainty  after  passing 
intervals  covered  with  detritus.  The  contact  with  the  metamorphic  rocks 
was  also  laid  down  and  numerous  dips  were  observed  in  the  metamorphic 
area.  In  order  to  eliminate  the  disturbing  influence  of  the  irregularities  of 
the  topography,  the  croppings  of  each  of  these  continuous  strata  and  the 
contact  of  the  metamorphic  were  reduced  to  their  intersections  with  normal 
planes  cutting  the  surfaces  respectively  at  the  mean  elevation  of  their  ex- 
posures. The  results  showed  that  adjoining  Chico  strata  are  parallel  and 
thrown  into  extremely  gentle  undulations,  while  the  metamorphic  area  is 
merely  a  shattered  mass  The  contact  has  approximately  the  same  general 
direction  as  the  Chico  beds,  but  does  not  entirely  coincide  with  their  strike. 
It  is  a  rough  line,  but  not  rougher  than  one  which  would  represent  the  ver- 
tical section  of  an  ordinary  sea-bottom  near  the  coast.  The  dip  of  the  Chico 
strata  decreases  as  the  distance  from  the  contact  increases. 

Either  this  structure  represents  a  non-conformity  or  else  the  metamor- 
phism  and  accompanying  disturbances  occurred  after  the  deposition  of  the 
Chico  beds,  but  ended  sharply  at  a  certain  line.  It  might  at  first  sight  seem 
impossible  that  an  area  several  miles  in  width  should  be  crumpled  and  broken 
quite  as  thoroughly  as  a  representative  area  of  the  Archaean  along  the  east- 
ern coast,  the  rocks  being  also  for  the  most  part  converted  into  serpentine 
and  chert,  and  that,  nevertheless,  both  mechanical  and  chemical  action 
should  cease  abruptly  at  a  given  line.  Yet  instances,  of  which  the  above 
might  pass  for  a  description,  actually  occur  and  are  perhaps  more  frequent 
in  the  Coast  Ranges  than  elsewhere.  All  geologists  who  have  visited  this 
region  are  aware  of  the  very  irregular  distribution  of  the  metamorphic 
areas,  and  it  has  already  been  pointed  out  that  the  metamorphic  rocks  pass 
over  into  unaltered  or  very  slightly  altered  Knoxville  beds  suddenly,  though 


190  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

under  circumstances  which  preclude  the  supposition  that  the  adjoining-  areas 
represent  different  formations.  There  are,  however,  significant  differences 
between  these  occurrences  and  the  conditions  at  New  Idria.  The  limits  of 
metamorphism  in  areas  consisting  of  Knoxville  beds,  however  sharp  they 
may  be,  are  exceedingly  irregular,  the  outline  being  substantially  inde- 
pendent of  stratification,  cutting  strata  more  often  than  following  them  and 
presenting  all  sorts  of  convolutions;  there  are  almost  invariably  also  out- 
lying areas  of  metamorphic  rock  and  included  masses  of  unaltered  rock; 
furthermore,  at  least  here  and  there,  distinct  transitions  occur  between  un- 
altered and  metamorphic  rock.  At  New  Idria,  on  the  other  hand,  a  section 
of  the  contact  normal  to  the  surface  extends  over  at  least  several  miles  (as 
far  as  it  was  followed)  in  a  tolerably  persistent  general  direction.  There 
are  no  outlying  patches  of  metamorphic  rocks;  the  included  masses  of 
comparatively  unaltered  rock  seem  wholly  different  from  the  Chico  strata 
above  them,  and,  though  there  is  a  considerable  alteration  of  a  portion  of 
the  overlying  mass,  this  alteration  is  not  of  the  same  character  as  the  mag- 
nesian  and  siliceous  metamorphism  of  the  underlying  rock;  nor  could  I 
find  any  distinct,  case  of  transition.  Finally,  as  has  already  been  men- 
tioned, in  the  Chico  conglomerates  a  part  of  the  pebbles  entirely  resemble 
the  silicified  or  jaspery  portions  of  the  present  metamorphic  area,  while  a 
few  are  both  rnacroscopically  and  microscopically  indistinguishable  from 
the  serpentinized  rocks  of  Knoxville  age 

Some  further  evidence  of  the  relation  of  the  two  series  was  found  a 
few  miles  to  the  southeast  of  New  Idria,  where'  a  branch  of  Cantua  Creek 
cuts  through  a  portion  of  the  range.  Here  the  heavy-bedded,  tawny  Chico 
sandstones,  lying  at  an  angle  of  about  30°,  cap  the  hills  which  are  inter- 
sected by  the  brook,  while  in  the  bed  of  the  stream  the  thin-bedded,  met- 
amorphic strata  stand  vertically.  No  actual  contact,  however,  could  be 
found,  the  interval  being  covered  with  detritus. 

There  seems  no  reasonable  explanation  of  the  structure  at  and  near 
New  Idria,  except  on  the  theory  of  a  non-conformity.  Though  the  evi- 
dence may  seem  less  satisfactory  than  that  which  would  be  presented  by  -an 
ideal  exposure,  it  is  derived  from  the  correlation  of  the  structural  evidence 
along  the  contact  for  miles,  and  in  tin's  respect  is  superior  to  any  but  that 


NON-CONFORMITY  BELOW  THE  CHIGO.  191 

furnished  by  the  very  best  local  exposures  of  unconformable  contacts;  for 
every  geologist  must  have  observed  cases  where  unconformable  exposures 
are  closelv  simulated  by  local  faults  Could  it  be  proved  that  the  under- 
lying mass  is  of  greater  age  than  the  Knoxville,  the  evidence  would  never- 
theless indicate  a  non-conformity  between  the  Chico  and  the  Knoxville, 
unless  it  could  be  shown  that  the  convulsion  which  has  so  marvelously 
crushed  the  Knoxville  beds,  at  least  from  Clear  Lake  to  the  neighborhood 
of  New  Almaden  and  again  at  San  Luis  Obispo,  was  unfelt  at  New  Idria, 
which  it  would  be  difficult  to  do,  in  view  of  the  fact  that  the  comparatively 
gentle  Post-Miocene  upheaval  certainly  extended  throughout  the  Coast 
lianges  of  California  and  Oregon. 

Mt.  Diablo  and  the  surrounding  country  consist  of  a  core  of  metamor- 
phic  rock  inclosed  nearly  or  quite  quaquaversally  by  rocks  of  Chico  and 
Tertiary  age.  The  core  is  highly  contorted  and  for  the  most  part  is  in  an 
extremely  metamorphosed  condition,  though  here  and  there  it  is  compara- 
tively fresh  and  in  some  cases  contains  Aucella  and  associated  fossils.  The 
overlying  Chico,  Tejon,  and  Miocene  strata  are  tilted,  but  otherwise  com- 
paratively undisturbed.  Over  wide  areas  these  three  series  seem  to  be  per- 
fectly conformable,  nor  have  I  seen  any  case  on  the  Pacific  Coast  where 
there  seems  any  ground  for  suspecting  a  non-conformity  within  these  limits. 
Mr.  Turner  spent  several  days  in  this  region,  collecting  fossils  from  various 
beds  and  searching  for  some  exposure  in  which  the  relations  of  the  Knox- 
ville beds  and  the  Chico  could  be  well  made  out.  The  result  was  negative, 
no  exposure  being  detected  from  which  a  non-conformity  could  be  conclu- 
sively established.  On  the  other  hand,  the  structure  is  much  more  easily 
accounted  for  by  supposing  a  non-conformity  to  exist  than  by  assuming 
conformity.  The  upturned  edges  of  the  more  recent  strata  form  long, 
smooth  curves,  enveloping  the  plicated  and  metamorphosed  core,  and  no- 
where was  there  any  metamorphism  in  the  strata  identified  as  Chico. 

On  the  coast  in  Sonoma  County,  about  two  miles  below  Ft.  Ross,  there 
is  a  sharp  contact  between  the  Wallala  beds  and  the  metamorphic,  serpen 
tinized  rock  which  extends  from  this  point  to  below  the  Russian  River,  if  not 
to  the  Golden  Gate.     Passing  back  into  the  hills,  the  Wallala  beds  are  found 
capping  the  iir^t  range  of  elevations  opposite  portions  of  the  shore,  which 


TJHIVBRSITY 


192  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

are  composed  of  the  metamorphic  rockg.  I  believe  no  one  could  examine 
this  locality  without  being  convinced  that  the  Wallala  beds  rest  unconform- 
ably  upon  the  metamorphic,  nor  could  any  one  pass  inland  from  the  mouth 
of  the  Russian  River  to  Knoxville  without  feeling'  sure  that  the  metamorphic 
is  uniform  in  character  and  substantially  continuous,  though  occasionally 
masked  by  eruptive  rocks  and  possibly  by  a  few  patches  of  unaltered  strata. 

There  is,  furthermore,  much  indirect  structural  evidence  that  a  non- 
conformity must  exist  between  the  Knoxville  beds  and  the  Chico.  Some- 
where between  the  end  of  the  Knoxville  and  the  beginning  of  the  Miocene 
there  was  a  great  upheaval,  accompanied  by  siliceous  and  magnesian 
metamorphism  and  followed  by  enormous  erosion,  for  at  many  points  the 
unaltered  Miocene  clearly  rests  unconformably  upon  the  metamorphic  rocks. 
This  I  have  observed  on  San  Bartolo  Creek  and  in  the  valley  of  the  San 
Benito,  to  which  the  other  is  tributary,  and  there  is  evidence  of  similar 
relations  at  Mt.  Diablo  and  at  New  Almaden.  Professor  Whitney  found  the 
Miocene  resting  uncornformably  upon  the  metamorphic  between  the  Guada- 
lupe  mine  and  Forbes's  mill,  and  also  near  McCartysville,1  as  well  as  north 
of  the  Golden  Gate,2  for  instance,  near  Tomales,3  while,  in  speaking  of  the 
neighborhood  of  Suscol,  he  says:4  "  It  is  probable  that  the  most  extensive 
disturbances  of  the  Cretaceous,  as  also  the  larger  portion  of  the  metamorphic 
action  upon  it,  had  taken  place  before  the  Tertiary  marine  and  volcanic 
beds  were  deposited." 

If  this  non-conformity  doas  not  occur  between  the  Knoxville  and  the 
Chico,  it  must  be  sought  between  the  Chico  and  the  Tejon  or  between  the 
Tejon  and  the  Miocene.  The  stratigraphical  relations  at  New  Idria  and  at 
Mt.  Diablo  show  that  there  was  continuity  of  sedimentation  from  the  Chico 
to  the  Tejon  and  the  organic  remains  prove  that  there  was  continuity  of 
life.  The  great  non-conformity  cannot,  therefore,  have  been  between  these 
groups.  Between  the  Tejon  and  the  Miocene  there  is  at  least  no  general 
non-conformity.5  Near  New  Idria  and  at  Mt.  Diablo,  for  example,  the  Mio- 

1  Geol.  Survey  California,  Geology,  vol.  1,  p.  69. 

2  Ibid.,  p.  79. 
1  Il.id.,  p.  83. 

« Ibid.,  p.  103. 

"Professor  whitiir.v  (Am-.  Grav.,  p.  'JG)  writes:  "Tlie  Miocen«ftndt4ieCretaceoB«»eeoi  everywhere 
to  be  couformable  with  eacll  other."    The  Crelaeecus  hero  rcf.tml  to  in  of  course  the  Tojon.     Mr.  .7. 


NON-CONFOKMITY  BELOW  THE  CI1ICO.  193 

cene  seems  as  strictly  conformable  with  the  Tejon  as  is  this  with  the  Chico. 
So,  too,  along  the  flank  of  the  Sierra  Nevada,  both  Chico  and  Miocene  re- 
main almost  perfectly  horizontal.  Had  there  bjen  a  great  upheaval,  accom- 
panied by  intense  metamorphism,  between— the  Tejon  and  the  Miocene,  it 
seems  impossible  that  no  Chico  or  Tcjon  strata  should  have  been  found 
metamorphosed. 

This  indirect  evidence  alone  would  seem  sufficient  to  establish  the  fact 
of  a  non-conformity  between  the  close  of  the  Knoxville  and  the  beginning  of 
the  Chico.  Add  to  this  the  direct  evidence  at  New  Idria  and  Ft.  Ross,  and 
the  conclusion  appears  irresistible,  irrespective  of  the  paleontologies!  argu- 
ment, which,  again,  of  itself  would  have  sufficed  to  lead  to  the  same  result. 

The  paleontological  argument  for  a  non -conformity  between  the  Knox- 
ville series  and  those  which  are  found  succeeding  it  may  be  very  briefly 
.stated.  Dr.  White  regards  the  fauna  of  the  Knoxville  group  as  lower  Neo- 
comian,  or  at  any  rate  as  not  later  than  this.  The  Chico,  in  his  opinion,  rep- 
resents the  very  latest  portion  of  the  Cretaceous  formation.  The  exposures 
at  Mt.  Diablo,  for  example,  show  that  there,  at  least,  no  deposits  now  inter- 
vene between  the  Knoxville  and  the  Chico.  Hence,  the  Knoxville  beds  at 
this  locality  must  have  been  above  water  in  the  interval.  If  this  interval 
had  been  a  short  one,  the  facts  could  be  explained  on  the  assumption  of  a 
mere,  gentle  oscillation  of  sea-level  relatively  to  the  land,  and  the  non-con- 
formity might  be  one  of  erosion,  or,  in  other  words,  would  not  necessarily 
imply  a  movement  of  great  structural  importance.  But  the  Knoxville  beds 
must  either  have  been  above  water  during  the  entire  interval  preceding  the 
Chico  or  during  a  sufficient  part  of  it  to  allow  of  the  removal  by  erosion 
of  any  strata  deposited  subsequent  to  the  close  of  the  Knoxville.  If  one 
supposes  denudation  to  be  as  rapid  as  se<li mentation,  which  could  hardly 
be  the  case  with  the  class  of  sediments  composing  the  Coast  Ranges,  the 
region  of  Mt.  Diablo  must  have  been  above  water  for  at  least  one-half  of 
the  interval  between  the  close  of  the  Knoxville  and  the  beginning  of  the 


Murcou  in  his  paper  on  geological  classification,  l?<tj-!,  p.  -I'J,  assorts  that  there  is  a  great  break  between 
the  Tejon  ami  the  Miocene  near  Ft.  Tejon.  In  the  description  of  the  locality  to  which  he  refers  (Ann. 
Kept.  Geog.  Surv.  West  of  the  100th  M.,  1876,  p.  167),  1  fiuil  no  mention  of  this  non-conformity.  In  the 
text  I  am  concerned  to  show  only  that  there  was  no  disturbance  at  this  epoch  great  enough  to  corre- 
spond to  the  metamorphism. 

MON   XIII 13 


194  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Chico.     Now  this  interval  is  an  enormous  one,  comprising  nearly  the  whole 
of  the  Cretaceous  period. 

The  Chico  represents  only  a  small  portion  of  the  Cretaceous,  vet  its 
sediments  are  thousands  of  feet  in  thickness.  The  same  is  true  of  the 
Wallala,  which  represents  a  different  portion  of  the  Cretaceous.  On  the 
most  unfavorable  supposition,  therefore,  Mt.  Diablo  must  have  been  ex- 
posed for  a  sufficient  time  and  at  a  sufficient  elevation  to  allow  of  the  ero- 
sion of  thousands  of  feet  of  strata  between  the  Knoxville  and  the  Ohico 
periods,  thus  indicating  not  a  gentle  oscillation,  but  a  great  uplift. 

Applied  to  the  quicksilver  belt  in  general  the  argument  is  less  precise 
and  indeed  negative;  for,  while  an  enormous  interval  of  time  elapsed  be- 
tween the  epochs  at  which  the  Knoxville  and  Chico  faunas  flourished,  it 
might  be  possible  to  find  other  intermediate  groups  as  well  as  the  Wallala. 
To  account  for  the  conditions  except  on  the  theory  of  a  non-conformity,  • 
however,  it  would  be  essential  to  find  such  faunas  in  beds  stratigraphically 
intercalated  between  the  Knoxville  and  the  Chico,  and  even  such  a  discovery 
would  not  disprove  a  non-conformity.  Now,  although  the  geology  of  the 
Coast  Ranges  has  by  no  means  been  exhaustively  studied,  they  have  been 
carefully  examined  at  a  great  number  of  points  by  main-  geologists  hold- 
ing diverse  views,  and  no  one  of  them  has  ever  discovered  a  trace  of  fos- 
siliferous  beds  stratigraphically  intercalated  between  the  Chico  and  the 
Knoxville  series.  It  is  therefore  very  improbable  that  a  substantially  full 
series  filling  the  gap  between  the  Knoxville  and  the  Chico  exists  in  any 
one  locality,  and  much  more  so  that  this  is  the  general  condition  and  that 
Mt.  Diablo  is  merely  a  local  exception. 

The  paleontological  argument,  though  negative,  is  thus  so  strong  as 
to  give  to  the  hypothesis  of  a  great  non- conformity  between  the  Knoxville 
and  the  Chico  a  very  high  degree  of  probability  without  any  aid  from 
direct  observations  of  non-conformity  or  from  observations  on  the  age  of 
the  metamorphosed  rocks. 

A  similar  argument  applies,  though  with  loss  force,  to  the  relations 
existing  between  the  Knoxville  and  the  Wallala,  for  here,  too,  a  long  inter- 
val is  indicated  between  the  eras  of  the  respective  faunas;  but  the  relations 
of  the  Knoxville  and  Horsetown  beds  cannot  as  yet  be  thus  elucidated,  be- 


NON-CON  KOUMITY   IJ10LOW  TIIK  CII1CO.  195 

cause  their  relative  age  is  not  sharply  enough  defined.  Unfortunately,  pos- 
itive structural  evidence  on  this  point  also  is  as  yet  wanting. 

The  evidence  of  the  existence  of  this  important  non-conformity  may 
be  recapitulated  in  a  few  words.  The  p"ebt>les  in  the  conglomerates  of  the 
\Vallala  and  the  Chico  groups  show  that  metainorphic  rocks  existed  near 
them  when  these  beds  were  deposited,  and  these  pebbles  entirely  resemble 
rocks  known  to  be  of  Knoxville  age.  If  they  are  really  of  this  age,  the 
metamorphisin  and  upheaval  of  the  Knoxville  beds  must  have  preceded  the 
Wallala  period  and  there  must  be  an  unconformity.  Again,  the  strati- 
graphical  relations  of  the  Wallala  beds  on  the  coast  and  of  the  Chico  beds 
at  New  Idria  to  the  adjoining  metamorphic  areas  seem  inexplicable  except- 
ing on  the  theory  of  a  non-conformity.  Furthermore,  a  great  non-con- 
formity certainly  exists  somewhere  between  the  Knoxville  beds  and  the 
Miocene.  None  such  is  found  between  the  Miocene  and  the  Tejon  or  be- 
tween the  Tejon  and  the  Chico.  Hence  the  non-conformity  must  be  be- 
tween the  Chico  and  the  Knoxville.  Finally,  the  fossils  prove  that  an  im- 
mense time  elapsed  between  the  end  of  the  Knoxville  and  the  beginning 
of  the  Chico,  while  the  Chico  is  now  found  in  contact  with  the  Knoxville 
at  various  points.  This  could  not  be  the  case  unless  an  upheaval  had  inter- 
vened. 

Identity  of  the  Mariposa  and  Knoxville  beds. TllC  gold  belt  of  California,  aS  llitliei'tO 

traced  out  by  miners  and  geologists,  is  an  area  of  peculiar  form.  From  Mari- 
posa County  to  Nevada  City,  in  Nevada  County,  a  distance  of  about  one 
hundred  and  fifty  miles,  the  belt  is  a  strip  of  country  nearly  parallel  to  the  crest 
of  the  Sierra  and  about  thirty  miles  in  width.  Northward  from  Nevada  City 
it  rapidly  widens,  becoming  at  the  same  time  less  well  defined.  To  the  north 
it  is  finally  terminated  by  extensive  lava  fields,  while  toward  the  northwest 
the  country  gradually  loses  its  auriferous  character  as  the  coast  is  approached. 
Within  the  gold-bearing  region  three  fossiliferous  areas  are  known  to  exist. 
From  the  McCloud  River  to  Pence's  ranch  extends  a  belt  of  highly  indu- 
rated limestone  containing  Carboniferous  fossils.  In  Genesee  Valley  the 
State  survey  found  fossils  regarded  as  Triassic  and  Jurassic.  Both  of  these 
localities  are  far  removed  from  the  narrow  strip  of  country  lying  along  the 
foot-hills  from  Mariposa  to  Nevada,  which  is  often  known  as  the  gold  belt 


196  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

proper.  The  fossiliferous  Mariposa  beds  already  mentioned  occur  near  the 
southerly  end  of  this  narrow  portion  of  the  auriferous  area. 

Previous  to  the  discovery  of  fossils  on  the  Mariposa  estate  in  the  series 
which  I  shall  call  the  Mariposa  beds,  Professor  Whitney  and  his  associates 
had  collected  in  the  Coast  Ranges  Belemnites,  a  shell  determined  as  Inoce- 
ramus  Piochii,  and  some  others,  from  the  strata  which  I  have  entitled  the 
Knoxville  beds.  Mr.  Gabb  described  them  as  Cretaceous  forms.1  Some 
years  after  Mr.  Meek  had  referred  the  Mariposa  beds  to  the  Jurassic  Mr. 
Gabb  redescribed  Inoceramus  Piochii  as  Aucella  Piochii,2  a  change  of  genus 
which  I  understand  to  be  unquestionably  correct.  This  correction  appeared 
to  me  at  the  very  beginning  of  this  investigation  of  great  importance  to 
the  stratigraphy  of  the  State,  for  through  it  the  fauna  of  a  large  part  of  the 
known  rocks  supposed  to  belong  to  the  Shasta  group  of  the  Cretaceous  ac- 
quired the  strongest  resemblance  to  the  fauna  of  the  Mariposa  County  Ju- 
rassic. Indeed  there  seemed  scarcely  room  left  for  a  distinction;  if  Aucella 
is  distinctively  Jurassic,  the  Aucella-'beaiing  beds  of  the  Coast  Ranges  must 
be  members  of  that  system,  while  if  these  Aucella  beds  are  Cretaceous  Au-, 
cella  is  not  a  distinctively  Jurassic  genus,  even  in  the  State  of  California, 
and  Mr.  Meek's  principal  reason  for  assigning  the  Mariposa  beds  to  the  Ju- 
rassic is  shorn  of  its  validity.  Dr.  White  afterwards  fully  confirmed  this 
view,  and  after  examination  of  Meek's  types,  together  with  new  and  better 
specimens  which  we  collected,  he  is  unable  to  draw  any  specific  distinc- 
tion between  the  Aucella  of  the  Mariposa  beds  and  that  of  the  Knoxville 
beds. 

Professor  Whitney  states  that,  while  the  Mesozoic  age  of  the  Mariposa 
beds  is  proved  by  their  fossils,  the  Pre-Cretaceous  age  of  these  strata  is  dem- 
onstrated by  their  stratigraphical  relations.  Professor  Whitney  has  indeed 
shown  that  Cretaceous  strata  rest  unconformably"  upon  the  upturned  -edges 
of  the  auriferous  slates  along  the  foot-hills  of  the  Sierra  at  several  points  ; 

1  Geol.  Survey  California,  Palaeontology,  vol.  1. 

2 Ibid.,  vol.2. 

3 1  am  perfectly  satisfied  of  the  existence  of  this  non-conformity,  though  the  localities  where  the 
Chico  bods  have  been  found  resting  ou  the  upturned  edges  of  the  auriferous  slates  are  not  near  those 
in  which  Mesozoic  fossils  have  been  found  in  the  older  rocks.  The  Chico  beds,  where  they  occur  along 
the  foot-hills,  have  suffered  little  if  at  all  from  the  Post-Miocene  uplift  in  the  Coast  Ranges  nii'l  are 
nearly  horizontal.  The  Mariposa  beds  are  almost  vertical. 


AGE  OP  THE  MAEIPOSA  BEDS.  197 

but  I  find  no  record  of  any  such  bed  so  low  as  the  Knoxville  group.1  All 
the  fossils  recorded  in  this  position  are  Chico.  This  does  not,  indeed,  pre- 
clude a  possibility 'that  the  Mariposabeds  are  Jurassic  and  the  Aucella  beds 
of  the  Coast  Ranges  Cretaceous,  for  the  former  might  have  been  above 
water  during  the  Shasta  epoch  ;  but,  were  Cretaceous  strata  containing  the 
.so-called  Aucella  Piochii  to  be  found  resting  in  a  nearly  horizontal  position 
upon  the  Mariposa  beds,  it  would  prove  not  only  that  the  genus  had  per- 
sisted from  Jurassic  into  Cretaceous  times,  but  that  in  essentially  the  same 
locality  the  genus  was  represented  immediately  after  a  great  and  widespread 
upheaval  by  a  species  nearly  or  quite  indistinguishable  from  one  which  had 
inhabited  it  prior  to  this  convulsion  and  the  attendant  metamorphism.  Zo- 
ologists would  think  such  a  survival  very  strange  if  it  could  be  proved  and 
highly  improbable  unless  the  proof  were  ample. 

On  the  other  hand,  if  the  Mariposa  beds  are  considered  as  equivalent 
to  the  Knoxville  beds  of  the  Coast  Ranges,  the  non-conformity  between  the 
Chico  beds  and  those  of  Mariposa  is  the  same  which  lias  been  traced  in  the 
.preceding  pages  as  existing  in  the  Coast  Ranges;  and,  even  if  the  species  of 
AiiccUa  found  in  the  respective  beds  were  different,  the  upheaval  and  meta- 
morphism of  the  two  series,  still  referable  to  nearly  the  same  period,  would 
be  presumptively  simultaneous. 

The  lithological  resemblance  of  the  rocks  of  the  Mariposa  estate  to 
those  of  many  portions  of  the  metamorphic  rocks  of  Knoxville  age  is  very 
strong.  There  is  a  similar  prevalence  of  thin-bedded  strata,  while  silicifica- 
tion  and  serpentinization  are  equally  the  predominant  characteristics.  Pli- 
cation and  fracture  are  less  noticeable  than  in  the  Coast  Ranges.  One 
geologist  has  maintained  that  the  fossiliferous  rocks  of  this  locality  do  not 
form  an  integral  portion  of  the  auriferous  series.  Neither  Dr.  White  nor 
I  was  able  to  see  any  ground  for  th'.s  assertion.  The  fossiliferous  rocks 
are  metamorphic,  like  the  entire  series;  they  have  the  same  dip  and 
strike  and  they  are  unquestionably  auriferous,  gold  quartz  veins  occurring 
between  the  fossil-bearing  strata  and  not  simply  near  them.  In  short, 
we  could  see  no  way  of  separating  the  strata  containing  shells  from  the 

1  The  shull  from  Tuscan  Springs  recorded  as  Inoceramtis  Piochii  (Geal.  Survey  California,  Geology, 
vol.  1,  p.  207)  is  redet.ermiued  :is  a  Mi/ til  an  in  il>id.,  vol.  a,  p.  191. 


198  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

remainder  of  the  immense  thickness  of  similar  and  apparently  conformable 
slates.1 

The  Knoxvilleand  Mariposa  series. TllOUgll  the  beds  of  tll6   KllOXville  cllld  Mtll'L- 

posa  groups,  which  on  the  structural  and  paleontological  grounds  already 
stated  are  considered  as  of  the  same  age,  appear  to  have  a  very  wide  distri- 
bution in  California,  particularly  along  the  two  great  mineral  belts  of  the 
State,  they  have  been  found  fossiliferous  at  only  a  comparatively  small 
number  of  localities  in  Lake,  Colusa,  Yolo,  Napa,  Solano,  Contra  Costa, 
Santa  Clara,  San  Luis  Obispo,  and  Mariposa  Counties.  Owing  to  the  ex- 
tremely disturbed  and  highly  metamorphosed  condition  of  the  greater  part 
of  the  series,  all  of  these  localities  are  of  very  restricted  area.  The  areas 
covered  by  unaltered  or  very  slightly  altered  rocks  apparently  of  the  same 
age  are  considerably  larger,  yet  even  these  are  small  and  seem  to  represent 
mere  patches  which  by  accidents  of  structure  have  escaped  the  general 
and  very  intense  metamorphism.  The  features  presented  by  the  rocks  of 
these  series  as  a  whole  are  somewhat  unusual  among  beds  so  recent,  and 
their  general  facies  has  led  some  able  and  experienced  geologists  to  suspect. 
for  them  a  far  greater  antiquity  than  is  warranted  by  the  detailed  evidence. 
Though  in  some  of  the  fossil  localities  shells  are  extremely  abundant, 
sometimes  making  up  a  large  portion  of  particular  strata,  the  number  of 
species  found  is  small,  and  of  the  short  list  which  can  be  enumerated  many 
are  so  imperfect  as  to  make  their  identification  doubtful  or  hopeless.-  The 
following  Avere  published  by  Mr.  Gabb: 

Belemnites  impressus  Gabb.  Liocium  jmnHutuni  Gabb. 

Pahcatractus  crassus  Gabb.  Modiola  major  Gabb. 

Csrdiera  mitraformis  Gabb.  AitecUa  Piochii  Gabb. 

Airesiug  lira-tits  Gabb.  Rhynchonella  \Vhitiieiji  Gabb. 

•RingineUa  polita  Gabb.  Pecten  complexicosta  Gabb. 


'  Mr.  J.  Marcou  stated  that  these  schists  "sont  sonvent  ties  ropproch&  des  veines  iiiotallit'ercs, 
sans  toutefois  jamais  en  renfermer"  (Bull.  Soc.  ge\>logi<|iio  Franco,  18s:!,  ]>.  410).  Ho  now  accepts 
without  ohjection  my  statement  that  gold  quartz  veins  occur  !><•!  wren  Ihe  slates  of  the  Mariposa  lit-ds, 
and  not  simply  near  them.  It  docs  not  follow,  lio  thinks,  that  because  the  Mai -iposa  beds,  which  in  liis 
opinion  are  Triassic,  form  an  integral  portion  of  the  auriferous  series,  the  apparition  of  gold  in  the 
Sierra  Nevada  is  to  be  put  as  late  as  the  Jurassic.  This,  in  his  opinion,  took  place  not  later  than  the 
Lower  Paleozoic.  "The  extrication  of  gold  from  tfte  quarlz  matrix  being  due  to  pressure,  naturally 
gold  dust  entombed  in  the  Triassic  marl  of  the  Mariposa  may  have  been  united  into  small  nuggets  dur- 
ing the  process  of  lamination  and  crushing"  (American  Geological  Cl-issiliention  etc.,  Hi-iS,  p.  :57).  I 
must  confess  myself  unable  to  follow  this  reasoning. 

2 The  paleontologieal  statements  are  all  on  the  authority  of  Dr.  White  and  are  in  part  extracted 
verbatim  from  Bull.  U.  S.  Geol.  Survey  No.  15. 


FAUNA  OF  THE  KNOXVILLE  SERIES.  199 

Three  other  species,  viz,  Ammonites  ramosus  Meek,  Potamides  diadema 
Gabb,  and  Lima  shastaensis  Gabb,  the  types  of  which  Gabb  obtained  in 
the  Horsetown  beds,  Dr.  White  thinks  probably,  but  not  certainly,  identical 
with  specimens  obtained  by  my  party  from  Knoxville. 

In  addition  to  these  published  species  the  following'  have  been  gener- 
ically  recognized  among  the  collections  from  Knoxville,  all  the  specimens 
of  which  are,  however,  too  imperfect  for  specific  determination:  Ammonites  f, 
Maryai-ita  /,  DeittaUinn,  Area,  Niiculana,  and  lihyncltondla.  Besides  all  these 
forms  there  are  fragments  among  the  collections  from  Knoxville  which 
indicate  two  or  three  other  molluscan  species  not  considered  in  the  enumer- 
ation of  the  fauna  of  the  Knoxville  beds.  The  specimens  which  have  been 
referred  to  as  probably  representing  a  species  of  Ammonites  are  only  a  few 
small  fragments,  which  show  only  portions  of  the  sides  and  periphery  of 
the  shell.  These  seem  to  indicate  a  species  related  to  the  A.  Newlcrryi  of 
Meek.  The  Dentulium  is  probably  undescribed,  as  are  probably  also  the 
Area  and  Nmulana.  The  Iiliywhonella  is  apparently  an  undescribed  species 
and  seems  to  be  identical  with  one  which  Dr.  White  discovered  at  Horse- 
town.1  The  collection  contains  only  one  fragment  of  a  shell  which  he 
refers  with  doubt  to  Margarita. 

The  specimens  of  Ammonites  which  in  the  foregoing  list  of  published 
species  are  referred  with  doubt  to  A.  ramosus  Meek  consist  only  of  the 
small  inner  whorls,  none  of  them  reaching  an  inch  in  diameter.  The  form, 
surface  markings,  and  septa  of  the  shell,  so  far  as  these  characters  are  shown 
by  the  Knoxville  specimens,  seem,  however,  to  agree  well  with  those  of  the 
species  as  it  is  described  by  both  Meek  and  Gabb.  Meek's  type  specimens 
came  from  Vancouver  Island,  but  Gabb  identified  the  species  in  the  Horse- 
town  beds  of  the  Shasta  group  of  California.2  The  specimens  of  .the  shell 
which  in  the  foregoing  list  are  referred  with  doubt  to  the  Potamides  diadema 
of  Gabb  are  embedded  in  compact  rock,  so  that  all  its  characters  cannot  be 
observed.  They  are  probably  identical  with  Gabb's  species  which  he  de- 
scribes as  coming  from  the  Horsetown  beds.  Finally,  so  far  as  the  specific 
identity  of  any  BeU'imiiti'*  can  be  determined,  there  seems  to  be  compara- 

1  This  form  is  closely  like  the  E.  oxi/oplirata  Fischer,  from  the  Jurassic  of  Moscow. 
*Soo  Bull.  V.  S.  Geol.  Sur.  Terr.  (1876)  No.  2,  p.  :571,  PI.  V,  Fig.  1;    also,  Geol.  Survey  California, 
Palaeontology,  vol.  1,  p.  65,  PI.  XI,  Fig.  II),  aiul  PI.  XII,  Fig.  12&. 


200  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

* 

tively  little  reason  to  doubt  that  the  specimens  which  have  been  found  in 
the  Horsetovvn  'and  Knoxville  beds,  respectively,  and  referred  to  Jlelemnitcs 
impressus  Gabb,  are  specifically  identical. 

Comparing  the  nineteen  species  of  fossils  now  known  to  exist  in  the 
Knoxville  beds  with  those  from  the  Horsetown  bods,  or,  in  other  words, 
with  all  the  other  species  which  Gabb  refers  to  the  Shasta  group,1  it  appears 
that  all  except  six  of  them  are  certainly  different  from  any  of  the  latter. 
One  of  these  six,  the  Ammonites  Nc/rbrri'i// ??,  offers  only  a  mere  suggestion 
of  identity ;  four  are  probably,  but  not  certainly,  identical,  namely,  Am- 
monites ramosusf,  Potamid's  diade.ma?,  Limn  sJiaxianisis?,  and  Rliynchondla 

?;  and  the  specific  identity  of  one,  Jii-lcnni'ili-s  in/)>ressus,  has  been 

regarded  as  certain.  The  fact  that  the  Bclenwites,  as  a  rule,  do  not  present 
salient,  or  even  satisfactory,  features  by  which  to  determine  specific  differ- 
ences, detracts  somewhat  from  the  certainty  of  the  last  identification. 

Dr.  White's  opinion  that  Amelia,  Erringtonii  and  A.  Piochii  Gabb  are 
specifically  identical  has  been  formed  after  he  had  had  better  advantages 
for  investigating  the  subject  than  seem  to  have  been  enjoyed  by  any  other 
person  who  has  written  upon  the  paleontology  of  California.  lie  has  not 
only  examined  the  original  types  of  those  two  forms,  but  hundreds  of  other 
specimens  of  A.  Piocl/ii  from  Gabb's  original  locality,  as  well  as  from  other 
places.  Furthermore,  we  made  a  personal  visit  to  the  locality  on  the  Mari 
posa  estate  where  the  type  specimens  of  A.  En-'nuitnmi  were  obtained,  and 
collected  better  specimens  of  it  from  the  auriferous  slates  there  and  in  the 
immediate  neighborhood  than  had  before  been  known.  We  also  obtained 
from  the  same  slates  fragments  of  an  ammonite,  some  impressions  of  a 
shell  apparently  the  Pholadomya  orlicuhita  of  Gabb,  others  that  represent  a 
species  of  the  Pectinida)  (perhaps  the  Amusxium  inn'i/nn  of  Meek),  and  still 
others  which  are  undeterminable.  On  adding  to  these  the  fielcnmitcs  pa- 
clficus  of  Gabb,  the  fauna  of  the  auriferous  slates  of  the  Mariposa  estate 
amounts  to  at  least  five  species  of  mollusks.  It  is  true  that  only  the  Aucella 
has  been  satisfactorily  identified  as  occurring  in  both  the  auriferous  slates2 

1  Geol.  Survey  California,  Paleontology,  vol.  2,  pp.  20D-254. 

1  Some  of  the  specimens  found  in  the  auriferous  slates  of  tho  Mariposa  estate  show  more  or  less 
distinct,  radiating  lines,  anil  tin-  saino  peculiarity  has  been  observed  among  examples  from  the  Knox- 
villo  beds,  as  wall  as  among  Russian  and  Alaskan  examples. 


FAUNA  OF  THE  KNOXVILLE  SERIES.  201 

and  the  Shasta  group,  but  there  is  nothing  in  the  character  of  the  other 
four  species  of  mollusks  from  the  auriferous  slates  which  would  render  in- 
consistent their  reference  to  the  age  of  the  Knoxville  beds. 

The  specimens  of  Aucclla  and  otFeir  auriferous  slate  species  just  re- 
ferred to  were  obtained  by  us  from  the  rocks  in  place,  those  found  near 
the  left  bank  of  the  Merced  Uiver,  Mariposa  County,  Gal.,  about  a  quar- 
ter of  a  mile  below  Benton's  mills,  being  especially  satisfactory  as  regards 
both  their  position  in  the  strata  and  their  condition  of  preservation.  Here 
the  strata  have  an  almost  vertical  dip  and  they  are  plainly  an  integral  part 
of  the  great  auriferous  slate  series.  A  part  of  our  collection,  as  well  as 
some  of  those  which  were  collected  by  King,  Gabb,  and  Miss  Erring- 
ton,  were  obtained  from  within  a  few  feet  of  the  famous  great  quartz  vein 
which  traverses  the  Mariposa  estate  and  which  is  inclosed  in  the  aurifer- 
ous slates. 

\Ve  did  not  obtain  any  Belemnites  from  the  auriferous  slates,  as  King 
and  Gabb  did,  nor  has  Dr.  White  seen  Gabb's  B.  pacificus,  obtained  from 
tliis  formation,  but  not  figured.  From  the  description  it  is  supposed  to  be 
identical  with  I>.  nuterittitix  White,1  obtained  by  Mr.  Dall  from  Alaska  and 
found  associated  with  an  AurcUa  regarded  as  of  the  same  species  as  A. 
Errnii/ton'ii  and  J.  Mncliii. 

That  the  Mariposa  beds  and  the  Knoxville  beds  are  of  the  same  age  is 
considered  as  proved  by  the  identity  of  Aucclla  Piochii  and  A.  Erringtonii, 
supported  by  the  general  character  of  the  other  fossils  which  the  strata  of 
both  respectively  bear.  It  is  true  that  this  is  the  only  specific  identifica- 
tion that  has  been  made;  but  the  species  in  question  is  one  of  extraordinarily 
wide  geographical  range  and  it  is  also  one  of  great  constancy  and  exclu- 
siveness  as  regards  its  distinguishing  characteristics. 

Certain  of  the  species  which  characterize  the  strata  of  the  Shasta 
group  in  California  have  been  recognized  among  the  collections  which  have 
been  reported  by  different  persons  from  Washington  Territory  and  British 
Columbia,  as  well  as  from  Alaska  and  the  Aleutian  Islands.  But  none  of 
the  species  of  that  group  has  been  found  in  any  North  American  strata  to 
the  eastward  of  the  Pacific  Coast  region,  if  we  except  Greenland.  While 

1  See  Bull.  U.  S.  Geol.  Survey  No.  4,  p.  13,  PI.  VI. 


202  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

it  is  probable  that  the  Horsetown  beds  of  California  are  represented  in 
those  northern  localities  which  have  been  referred  to,  it  is  more  especially 
the  equivalent  of  the  fauna  of  the  Knoxville  beds  that  has  been  recognized 
as  existing  there.  This  recognition  is  mainly  through  the  identification, 
among  the  collections  which  have  been  made  there,  of  the  AuceUa,  which 
so  strongly  characterizes  the  Knoxville  division  of  the  Shasta  group  in 
California.  Specimens  regarded  as  specifically  identical  with  the  form 
which  Mr.  Gabb  published  under  the  name  of  AuceUa  Ploclni  have  been 
presented  to  the  Survey  by  Prof.  Thomas  Condon,  which  he  collected  at 
Puget  Sound,  Washington  Territory.  These  specimens  were  in  bowlders, 
but  they  nevertheless  indicate  the  existence  of  an  otherwise  unknown 
locality  to  the  north  of  Oregon.  Mr.  Whiteaves  refers  to  the  same  species 
as  being  abundant  at  Tatlayoco  Lake  and  other  places  in  British  Columbia,' 
and  Professor  Eichwald,  Dr.  P.  Fischer,  and  Dr.  White  have  published 
forms  from  different  parts  of  Alaska  which  the  last  regards  as  specifically 
identical  with  it. 

Among  the  fossils  collected  in  Alaska  by  Peter  Doroschin,  Eichwald2 
recognized  all  the  forms  of  Amelia  which  Keyserling  had  published  as 
occurring  in  Russia,  namely,  A.  'concentrica  Fischer,  A.  mosqucnsis  von 
Buch,  A.pallasii,  and  A.  crasslcollis  Keyserling.  The  last  two  he  considered 
as  only  varieties  of  A.  concentrica.  Dr.  Fischer  recognized  only  one  species 
among  Pinart's  Alaskan  collections,3  which  he  referred  to  A.  concentrica. 

Dr.  White  also  recognized  only  one  species  among  the  collections 
brought  from  Alaska  by  Mr.  Dall.  Although  the  specimens  were  numerous 
and  presented  quite  a  wide  variation  of  form,  he  regarded  them  all  as  repre- 
senting a  variety  of  AuceUa  concentrica.4  Mr.  Whiteaves  (loc.  cit.)  recog- 
nized only  one  species  among  the  collections  from  British  Columbia,  and 
this  he  referred  to  Amelia  mosqucnsis. 

In  the  Knoxville  beds  of  California  there  are  two  recognizable  varieties 
of  AttccUa,  which  are  connected  more  or  less  closely  by  intermediate  forms, 

1  See  Trans.  Koyal  Soc.  Canada,  sec.  4,  18-32,  p.  84. 

2SeoGeoguo8t.-paIaeout.  Bemerkmigen  iiberdio  Halliinscl  Mangmulilak  inul  (lit-  alcut  iscln-n  Inscln, 
1871,  pp.  185-187,  PI.  XVII. 

3  See  Voyage  a  la  c6te  nord-onest  do  I'Aiuc'rique,  par  M.  Alph.-L.  Piuart,  pp.  33-30,  PI.  A. 

4  Sen  Bull.  U.  S.  Geol.  Survey  No.  4,  pp.  13,  14,  PI.  VI. 


AUCELLA.  203 

but  are  decidedly  different  in  extreme  examples.  It  is  usually  the  case  also 
that  one  variety  will  be  found  to  prevail  in  certain  layers  of  rock,  some- 
times almost  exclusively,  and  the  other  variety  in  other  layers. 

Adult  examples  of  one  of  these  varieties  are  large,  robust,  and  often 
inflated.  These  approach  the  typical  forms  of  A.  concentrica  more  nearly 
than  the  others.  Those  of  tlie  other  variety  are  smaller,  more  slender,  and 
have  a  more  delicate  appearance.  They  seem  to  correspond  more  nearly 
with  the  type  of  A.  mosqucnsis.  Still,  after  examining  numerous  examples 
from  Alaska,  British  America,  Washington  Territory,  and  California, 
besides  some  Russian  examples  of  A.  concentrica  and  A.  mosquensis,  believed 
to  be  authentic,  in  the  collections  of  the  Smithsonian  Institution,  Dr.  White 
is  of  the  opinion  that  all  of  them  represent  only  one  species.  Indeed,  he  is 
disposed  to  regard  as  at  most  only  varieties  of  one  species  all  the  forms 
which  have  from  various  authors  received  the  names  Aucella  concentrica, 
A.  )it»*t//u'iisis,  A.  pallasii,  A.  crassicollis,  A.  Fiochii,  and  A.  Erringtonii. 
However,  it  will  be  convenient,  when  discussing  the  Aucetta-bear'mg  strata 
of  California,  to  retain  the  names  A.  concentrica  and  A.  mosquensis  to  indi- 
cate the  more  robust  and  the  more  elongate  forms,  respectively,  as  they 
occur  in  that  State. 

Before  dismissing  this  reference  to  Aucella,  it  is  well  to  note  how  wide 
i-i  the  geographical  distribution  of  the  variable  form  which  has  been  known 
under  the  various  names  which  have  just  been  mentioned.  This  shell  was 
first  known  in  various  parts  of  Russia  and  subsequently  upon  the  eastern 
coast  of  the  Caspian  Sea,1  in  northern  Siberia,2  on  the  island  of  Spitzbergen,3 
on  Kuliii  Island  (off  the  east  coast  of  Greenland),4  and  in  Alaska,  British 
Columbia,  Washington  Territory,  and  southward  to  central  California,  as 
mentioned  on  previous  pages.  Although  it  is  so  variable  in  certain  of  its 
features,  so  constant  is  it  in  its  general  characteristics  and  so  distinct  from 
related  forms  that  paleontologists  are  now  generally  agreed  as  to  its  identity 
in  all  the  widely  separated  localities  which  have  just  been  indicated. 

'See     Kiclnvald's   Geognost.-palaeont.    Hiiiiierknngru    fiber  die.    llalbinsel    Mangisrliliik    uticl   die 
alentischen  Inseln,  1871,  p.  53. 

See  MicldendorlV's  1,'eise  in  dc'ii  aussei-si.e.ii  Nordeu  and  Ostcn  Siliri  ..ins,  vol.  1,  parl  1,  p.  255. 

:'See  Lindstroin  :   Oin  Trias-  och  Jurafur.stRning.tr   Iran    Spetsbergen,   Kongl.  svensk.   Vot.-Akad. 
TTandl..  vol.  (i.  No.  (i,  1.-C7,  p.  14. 

1  See  F.  Tonlu,  Die  zweite  dcutsclio  Nordpolarfahrt,  vol.  2,  Ib74,  pp.  497-505;   also  Quart.  Jonr. 
Cicol.  Sor.  London,  vol.  I)  I,  1*7»',,  p.  5CiO. 


204  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

The  age  of  the  Aucetta-be&ring  beds,  whether  in  California  or  else- 
where, is  not  fully  determined,  apparently  on  account  of  the  equivocal  char- 
acter of  the  faunas  associated  with  this  fossil. 

Both  Eichwald  and  Whiteaves  contend  that  all  the  strata  which  bear 
Aucclla  conccntrica  and  A.  mosquensis  are  certainly  of  Neocomian  age.  On 
the  other  hand,  Keyserling,  Trautschold,  D'Orbigny,  and  others  as  confi- 
dently assert  that  they  are  of  Jurassic  age  and  many  paleontologists  have 
hitherto  regarded  Aucclla  as  an  exclusively  Jurassic  genus.  Even  so  late 
as  the  year  1881  Mr.  A.  Pavlow,  a  member  of  the  official  geological  com- 
mission of  Russia,  placed  in  the  Jurassic  series  the  well  known  strata  which 
in  eastern  and  other  parts  of  Russia  besur  Aucella  conccntrica,  as  the  earlier 
Russian  geologists  also  did.1 

Dr.  White  thinks  it  not  impossible  that  Aucclla  occurs  in  the  Jurassic 
in  some  regions  and  in  the  Neocomian  in  others,  just  as  a  number  of  Lower 
Carboniferous  species  of  Europe  are  found  in  the  Upper  Carboniferous  of 
North  America  and  as  certain  species  are  known  to  pass  from  the  Devonian 
to  the  Carboniferous.  lie  inclines,  however,  to  the  opinion  that  the  Cali- 
fornia occurrences  are  referable  to  the  Lower  Neocomian,  which,  as  has 
been  seen,  is  substantially  the  result  at  which  Gabb  arrived  for  the  group 
here  called  the  Knoxville  series. 

As  has  been  seen,  the  age  of  the  metamorphic  series  of  the  Coast 
Ranges  (which  is  that  most  usually  associated  with  the  quicksilver  deposits), 
the  age  of  a  highly  important  portion  of  the  auriferous  slates  of  California, 
and  consequently  also  the  structural  relations  of  the  Coast  Ranges  and  Sierra 
Nevada  depend  almost  entirely  upon  two  closely  allied  species,  or- on  two 
varieties  of  a  single  species,  of  Aucclla.  The  very  great  importance  which 
this  fossil  thus  acquires  is  much  increased  by  the  fact  that  it  occurs  along 
the  Pacific  Coast  at  various  points  up  to  Alaska,  a  distance  of  about  two 
thousand  miles,  and  again  at  very  widely  separated  points  in  Europe. 

In  the  hope  that  it  may  lead  to  a  more  extended  knowledge  of  the 
distribution  of  this  peculiar  and  important  fossil,  I  have  induced  Dr.  White 
to  prepare  a  description,  with  illustrations,  of  Aucclla,  which  appears  as  an 
appendix  to  1  his  chapter. 

1  Sec  Bull.  Soc.  gdologique  Franco,  M  series,  vol.  12,  1884,  pp.  6S6-G9G. 


UORSETOWN  BEDS.  205 

The  Horsetown  beds. — The  Ilorsetown  beds,  as  it  seems  convenient  to  call 
tlie  group  which  occurs  near  Cottonwood  Creek,  Shasta  County,  are  con- 
fined to  that  locality,  so  far  as  known,  and  their  stratigraphies!  relation  to  the 
Knoxville  series  is  undetermined.  The  solution  is  very  probably  to  be 
found  in  the  eastern  Coast  Ranges  in  Tehama  County,  but  this  region  is  not 
known  to  have  been  geologically  explored  and  it  probably  will  not  be  ex- 
amined until  a  special  study  of  the  Coast  Ranges  as  a  whole  is  undertaken. 
The  Horsetown  beds  are  somewhat  altered,  but  at  the  points  visited  by 
Dr.  White  and  myself  they  do  not  show  the  characteristic  serpentinization 
and  silicification  of  the  metamorphosed  Knoxville  beds.  It  cannot  by  any 
means  be  asserted  definitely,  however,  that  they  were  not  involved  in  the 
upheaval  and  metamorphisin  which  took  place  after  the  Knoxville  and  be- 
fore the  Wallala  period,  because  much  of  the  Knoxville  series  is  also  little 
altered.  On  the  other  hand,  the  Horsetown  beds  rest  unconformably  upon 
the  auriferous  slates  of  that  region,  which  are  of  uncertain  age,  though  ap- 
parently continuous  with  the  Carboniferous  of  Pence's  ranch.  Professor 
Whitney  detected  this  non-conformity,  though  expressing  the  result  in  some- 
what guarded  terms.1  The  mining  operations  which  have  since  been  pros- 
ecuted have  so  exposed  the  rocks  as  to  leave  no  room  for  any  possible 
difference  of  opinion.  The  slates  upon  which  the  Horsetown  beds  lie  are 
somewhat  peculiar  and  differ  physically  from  those  of  the  Mariposa  beds, 
showing  a  very  thin  cleavage  and  an  unusual,  silver-gray  luster.  They  give 
to  the  eye  an  impression  of  great  geological  age.  The  fauna  of  the  Horse- 
town  beds  includes  the  whole  of  Gabb's  Shasta  group,  excepting  the  species 
already  enumerated  as  belonging  to  the  Knoxville.  Mr.  Gabb  and  Dr. 
White  agree  in  considering  the  affinities  of  these  fossils  to  be  with  those 
of  the  Gault,  and  therefore  decidedly  later  than  the  Knoxville  series. 
Though  the  Ilorsetown  beds  lie  not  far  from  the  general  line  of  the  quick- 
silver belt,  they  are  not  known  to  occur  anywhere  in  close  connection  with 
the  ore  deposits. 

The  cascade  Range. —  It  is  hardly  possible  to  contemplate  the  close  relation 
shown  to  subsist  between  the  eastern  and  western  ranges  of  central  Cali- 
fornia without  inquiring  what  connection,  if  any,  exists  between  them 

1  Geol.  Survey  California,  Geology,  vol.  1,  p.  321. 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

and  those  north  and  south  of  the  great  valley  of  the  State.  Dr.  White 
and  I  therefore  visited  Oregon  and  made  several  trips  into  the  mountains 
of  the  Cascade  Range  from  Roseburg. 

The  sedimentary  rocks  appear  to  be  underlain  by  granite,  for,  though 
we  did  not  meet  with  this  rock  in  place,  it  constitutes  a  large  proportion  of 
the  stream  pebbles.  It  is  stated  on  the  excellent  authority  of  Rev.  Thomas 
Condon  to  occur  in  place  somewhat  to  the  northward  of  this  point.  In 
a  great  number  of  localities  we  found  upturned,  crumpled,  silicifiecl,  and 
metamorphosed  rocks  exactly  similar  to  those  of  Mt.  Diablo,  but  our  search 
for  Aucella  was  not  rewarded.  Upon  the  metamorphic  rocks  lie  uncon- 
formably  somewhat  tilted,  unaltered  sandstones.  These  are  certainty  Mio- 
cene, for,  though  we  found  no  fossils  ourselves,  Dr.  White  examined  ex- 
tensive collections  of  Miocene  shells  in  entirely  similar  rock  made  by 
Rev.  Thomas  Condon,  who  gave  us  full  information  as  to  their  occurrence 
in  precisely  similar  positions,  but  somewhat  north  of  Roseburg.  Overlying 
the  sandstones  are  large  areas  of  volcanic  rocks.1 

In  the  section  made  by  the  Columbia  River  no  metamorphic  rock  or 
granite  appears,  but  at  least  the  southern  portion  of  the  range  has  a  foun- 
dation similar  to  that  of  the  California  Coast  Ranges,  and,  as  I  think,  prob- 
ably of  the  same  age.  This  cannot  be  stated  as  a  certainty  until  AuceUa 
has  been  found  in  the  Cascades;  but,  considering  that  this  fossil  certainly 
occurs  near  Puget  Sound  and  that  the  lithological  character  and  geological 
association  of  the  metamorphic  rocks  at  Roseburg  are  indistinguishable 
from  those  of  known  Neocomian  localities  in  the  Coast  Ranges,  no  grave 
doubt  remains. 

Chico  beds,  however,  occur  in  central  Oregon,  and  on  this  ground  the 
Blue  Mountains  have  been  regarded  as  the  northerly  continuation  of  the 
Sierra.2  But  shore  lines  and  lines  of  structure,  though  intimately  associated, 
do  not  always  coincide.  A  depression  of  only  30  feet  to-day  would  put 
Sacramento,  Stockton,  and  an  immense  area  of  the  Great  Valley  under 
water,  while  a  depression  of  400  feet  would  convert  the  Great  Valley  into 

1  In  answer  to  an  inquiry,  Prof.  Joseph  Le  Conte  states  that,  his  remarks  concerning  the  lower  por- 
tion of  the  Cascade  Range  in  Am.  Jour.  Sci.,  3d  series,  vol.  7,  p.  177,  were  not  from  personal  ohserva- 
tion.  He  there  suggested  that  the  Cascades  were  a  continuation  of  the  Sierra. 

1  U.  8.  Geol.  Expl.  40th  Parallel,  Systematic  Geology,  vol.  1,  p.  4f>si. 


UNIVERSITY 


THE  CASCADE 

a  gulf,  extending  from  Tulare  Lake  to  above  the  town  of  Red  Bluff.  There 
is,  indeed,  abundant  reason  to  suppose  the  Great  Valley  did  form  such  a 
sheet  of  water  within  the  recent  period,  for  the  marsh  lands  bordering  on 
the  lower  Sacramento  and  San  Joaquin  llivers  seem  mere  continuations  of 
the  mud  flats  of  the  Bay  of  San  Francisco  exposed  at  low  tide,  and  the 
relations  of  the  alluvial  plains  to  the  neighboring  hills  are  indicative  of  the 
same  conditions,  while  the  character  of  some  of  the  terraces  on  the  sea- 
coast  demonstrates  that  the  sea-level  not  long  ago  was  at  least  over  200 
feet  higher,  relatively  to  the  land,  than  it  is  now.1 

There  would  be  nothing  strange,  therefore,  in  the  discovery  of  brack- 
ish-water shells  or  even  salt-water  remains  in  the  alluvium  of  the  Great 
Valley,  but  this  would  not  indicate  that  the  Coast  Ranges  were  non-existent 
at  the  time  when  such  mollusks  were  alive.  So,  also,  the  Gulf  of  California 
now  extends  some  one  hundred  and  fifty  miles  to  the  eastward  of  the  true 
coast  line,  or  the  western  limit  of  Lower  California.  The  fact  that  Chico 
fossils  are  found  in  central  Oregon  only  proves,  therefore,  that  tlie  Cas- 
cades must  have  been  broken  through  at  one  or  more  points  during  this 
period,  and  not  that  this  range  is  more  recent  than  the  Chico. 

Southern    continuation  of  the   Coast   Ranges. Tll6    main     Structural     Continuation  of 

the  united  Coast  Ranges  and  Sierra  Nevada  to  the  southward  appears  to 
be  the  peninsula  of  Lower  California.  Mr.  Gabb,2  who  visited  this  region, 
stated  that  it  is  possible  to  trace  an  uninterrupted  granite  ridge  from  the 
San  Gabriel  Mountains,  north  of  Los  Angeles,  through  Los  Angeles,  San 

1  Prof.  George  Davidson  has  traced  from  Lower  California  to  Alaska  the  terraces  which  line  the 
wi-stfni  coast  (1'roc.  California  Acad.  Nat.  Sci.,  vol.  5,  p.  DO).     So  great  is  the  regularity  of  the  surfaces 
of  some  of  these  terraces  that  he  feels  compelled  to  deny  that  they  have  been  cut  by  wave  action.     He 
considers  it  probable  that  ice  was  the  agent.     My  own  opportunities  for  examining  these  terraces  have 
been  very  limited,  but  in  the  region  between  Ft.  Ross  and  Gualala  I  have  studied  them  with  some  care. 
Their  topography  appeared  to  me  indistinguishable  from  that  of  the  beaches  exposed  at  low  water,  and 
iit  two  points  I  detected  Pholas  borings  on  the  terraces  at  a  distance  of  several  miles  from  one  another. 
One  of  these  points  was  by  estimation  150  feet  and  the  other  250  feet  above  sea-level.     However  the 
terraces  of  this  region  were  formed,  therefore,  they  have  been  at  sea-level  within  a  period  which  has 
been  insufficient  to  obliterate  extremely  superficial  markings  in  a  very  soft  sandstone.     Neither  in  this 
region  or  at  Santa  Cruz  nor  on  the  Farallone  Islands  was  I  able  to  see  the  necessity  for  attributing  the 
excavation  of  the  terraces  to  any  other  agency  than  that  of  the  waves.     That  there  are  such  terraces 
for  which  wave  action  may  seem  an  inadequate  explanation  I  do  not  of  course  deny;  yet,  if  the  level 
of  the  coast  were  to  remain  absolutely  constant  for  a  very  long  period,  it  appears  to  me  that  hard  rocks 
and  soft  must  eventually  be  cut  away  to  a  very  nearly  uniform  depth.     Mr.  Goodyear  (ibid.,  vol.  4,  p. 
295)  has  called  attention  to  evidences  of  oscillation  in  the  level  of  the  coast  of  Oregon. 

2  Geol.  Survey  California,  Geology,  vol.  2,  appendix,  p.  137. 


208  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Bernardino,  and  San  Diego  Counties,  into  Lower  California  and  along 
the  peninsula  to  within  a  few  miles  of  the  old  mission  of  Santa  Gertrudis, 
while,  from  the  exposure  through  denudation  at  Santa  Gertrudis  and  again 
near  Loreto,  it  is  probable  that  between  the  mission  and  Cape  San  Lucas 
the  granite  nowhere  lies  at  a  greater  depth  than  1,000  feet.  Dr.  White  has 
pointed  out  that  fossils  of  the  Atlantic  Cretaceous  fauna,  which  is  entirely 
distinct  from  the  fauna  of  the  Pacific  Cretaceous,  are  found  on  the  western 
side  of  the  Sierra  Madre  of  Mexico,  thus  showing  that  Lower  California 
was  during  the  Cretaceous  the  dividing  isthmus  between  the  oceans  and 
confirming  Gabb's  view.  . 

Though  the  probabilities  are  thus  strongly  in  favor  of  the  theory  that 
the  Cascades  and  the  mountains  of  Lower  California  are  the  main  struct- 
ural continuations  of  the  united  Sierra  and  Coast  Ranges,  it  by  no  means 
follows  that  these  ranges  form  an  isolated  system  or  that  these  continua- 
tions of  the  California  mountains  are  the  only  ones.  On  the  contrary, 
there  is  much  evidence  that  the  Sierra  is  inseparable  from  the  basin  sys- 
tem, which  appears  to  continue  through  Arizona  and  to  unite  with  the 
Rocky  Mountain  system.  Too  little  is  known  of  northern  Mexico  and 
the  territory  of  the  United  States  immediately  adjoining  it  lo  justify  any 
extended  speculation  on  this  subject, 

Pre-Cretaceous  upheavals  and  metamorphism. TwO  important  ai'OaS  of  SCrpeiltillized 

and  silicified,  metamorphic  rocks  have  been  shown  in  the  foregoing  pages 
to  be  of  the  same  age,  probably  Neocomian,  and  it  has  been  established 
that  these  series  were  upheaved  and  metamorphosed  prior  to  the  deposition 
of  the  Wallala  beds,  regarded  by  Dr.  White  as  Turonian.  But  there  are 
other  metamorphic  rocks  in  California  deposited  long  before  the  Neocomian. 
Thus  the  Carboniferous  limestones  on  the  McCloud  River  are  ciystalline 
and  the  metamorphic  shales  near  Pence's  ranch,  in  Butte  County,  are  at 
least  in  part  Carboniferous.  They  bear  considerable  similarity  to  those  of 
the  Mariposa  group,  and,  furthermore,  they  are  nearly  vertical  and  strike  in 
nearly  the  same  direction  as  those  of  the  gold  belt  proper.  The  cniestion 
therefore  at  once  arises  whether  their  upheaval  and  metamorphism  are 
ascribable  to  the  same  period  as  the  uplift  and  alteration  of  the  Mariposa 
and  Knoxville  beds. 


PERSISTENCE  OF  THE  SIERRA  NEVADA.  209 

It  is  hoped  that  work  now  being  done  on  the  gold  belt  may  afford  a 
definite  answer  to  this  and  other  questions.  In  the  absence  of  distinct 
evidence,  however,  the  probabilities  appear  to  be  against  the  supposition 
that  all  the  metamorphism  which  can  be  traced  in  this  State  is  referable  to 
a  single  period. 

It  may  be  asserted  with  some  confidence,  as  a  result  of  all  the  geologi- 
cal work  done  from  the  Rocky  Mountains  to  the  Pacific,  that  there  has  been 
throughout  geological  time  a  definite  tendency  in  the  structural  development 
of  this  area.  The  geologists  of  the  fortieth  parallel  exploration  showed 
that  a  fault  began  upon  the  west  flank  of  the  Wahsatch  in  the  Archean,  the 
same  fault  which  Mr.  Gilbert  has  traced  as  still  in  progress.  The  last- 
named  geologist  and  Prof.  Joseph  Le  Conte  have  also  detected  a  similar 
fracture  on  the  east  side  of  the  southern  portion  of  the  Sierra.  The  eastern 
portion  of  the  Great  Basin  was  lifted  above  the  surface  of  the  ocean  after 
the  close  of  the  Carboniferous,  the  western  portion  of  the  same  area  fol- 
lowed before  the  Cretaceous,  and  at  one  or  both  of  these  epochs  the  coun- 
try was  laterally  compressed,  an  action  no  doubt  closely  connected  with 
the  progress  of  the  great  faults.  About  the  time  of  the  Neocomian  Cal- 
ifornia experienced  an  east  and  west  compression,  and  again  at  the  close  of 
the  Miocene  an  uplift  threw  the  horizontal  strata  of  the  coast  into  north  and 
south  folds.  From  the  Wahsatch  to  the  Pacific  Coast  there  thus  appears 
to  have  been  a  recurrent,  if  not  a  constant,  tendency  to  lateral  compression 
in  substantially  one  and  the  same  direction  and  to  an  increase  of  the  land 
area  west  of  the  Wahsatch. 

This  repetition  of  movements  in  a  similar  direction  has  tended  to  ob- 
scure the  time  relations  of  geological  phenomena,  particularly  along  the 
great  Sierra  Range,  which  has  probably  been  one  of  the  most  persistent 
topographical  features  of  the  continent.  Dr.  White  points  out  that  an  ex- 
traordinary difference  has  existed  between  the  marine  fauna  of  the  Pacific 
Coast  and  that  of  the  waters  east  of  the  Sierra  from  a  time  prior  to  the 
Cretaceous  onward,  and  hence  that  a  land  barrier  must  throughout  have 
occupied  substantially  the  position  of  the  Sierra  Nevada,  which  must  there- 
fore have  experienced  repeated  upheavals  to  compensate  for  constant  ero- 
sion. There  are  also  said  to  be  some  paleontological  grounds  for  sup- 
MON  xi n 14 


210  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

posing1  at  least  a  partial  separation  of  these  areas  daring1  the  Carboniferous. 
This  supposition  is  in  entire  accord  not  only  with  the  structural  anal- 
ogies of  the  region,  but  with  the  detailed  observations  of  Mr.  Clarence 
King1  and  his  colleagues,  who  were  led  to  infer  the  existence  of  a  conti- 
nental area  during  the  Paleozoic  west  of  longitude  117°  30',  in  latitude  40°. 
Such  a  range  as  the  Sierra,  though  partaking  in  the  general  compression 
and  movement  of  the  whole  country,  must  offer  a  tremendous  resistance, 
and,  at  any  one  of  the  active  periods  during  which  the  physical  conditions 
permitted  contortion  of  strata  along  the  western  flank  of  the  Sierra,  these 
must  have  been  driven  against  the  barrier  until  they  could  yield  no  more. 
Thus  if  a  pile  of  cloths  were  compressed  from  their  edges  (as  in  Hall's 
famous  experiment)  with  enormous  energy,  they  would  be  forced  into 
plications  so  sharp  that  the  dip  at  any  point  would  be  nearly  vertical  It 
seems  to  follow  that  at  different  upheavals  (some  of  them  perhaps  as  yet 
untraced)  strata  to  the  west  of  the  great  Sierra  may  have  been  driven  into 
the  nearly  vertical  position  of  the  gold  slates,  their  original  stratigraphical 
relations  thus  becoming  completely  obscured.  I  do  not  consider  it  certain, 
therefore,  or  even  probable,  that  the  Carboniferous  slates  near  Pence's 
ranch  first  assumed  their  present  position  subsequently  to  the  Knoxville 
period.  It  may  be  that  they  have  stood  nearly  as  now  ever  since  the  Car- 
boniferous of  Utah  was  raised  above  water,  while  the  slates  of  Horsetown, 
of  the  age  of  which  nothing  is  known,  may  possibly  owe  their  vertical  dip 
to  still  earlier  convulsions. 

The  Carboniferous  slates  of  Pence's  ranch  are  serpentinoid,  and, 
though  distinctions  between  them  and  the  metamorphosed  Knoxville  beds 
might  perhaps  be  drawn,  the  rocks  are  very  similar.  But,  just  as  it  seems 
to  me  that  successive  upheavals  may  have  produced  similar  effects  upon  the 
arrangement  of  strata,  I  think  the  association  of  a  certain  uplift  with  a  par- 
ticular series  of  chemical  changes  tends  to  show  that  analogous  dynamical 
conditions  might  lead  to  molecular  changes  of  the  same  kind.  It  seems 
therefore  not  at  all  impossible  that  both  upheaval  and  metamorphism  at 
Pence's  ranch  were  in  the  main-  earlier  phenomena  than  those  traced  in  the 
Coast  Ranges.  If  so,  their  effect  must  have  been  felt  throughout  a  great  por- 

•  U.  P.  (!<•"'.  Kxi'l.  40th  Parallel,  vol.  1,  Systematic  Geology,  p.  534. 


THE  COAST  L'AXGES  AND  THE  SJEKKA.  211 

_ 

tion  of  California,  though  the  results  in  the  Coast  Ranges  may  have  long 
since  been  obliterated.  On  the  other  hand,  the  post-Knoxville  disturbance 
must  have  been  felt  at  Pence's  ranch,  though  its  effects  may  have  been 
trifling  as  compared  with  those  of  earlier  convulsions. 

The  Coast  Ranges  members  of  the  western  Cordillera  system. As  hag  already  bcCll  Stated, 

I  am  unable  to  see  any  reason  for  dissenting  from  Professor  Whitney's 
opinion  that  the  fossiliferous  beds  of  Mariposa  form  an  integral  portion  of 
the  modern  Sierra  Nevada  range.  It  seems  simply  impossible  that  they 
should  have  assumed  their  present  vertical  position  with  a  strike  parallel 
to  the  crest  and  that  they  should  have  been  profoundly  modified  by  chem- 
ical action,  except  under  conditions  of  disturbance  amply  sufficient  to  bring 
abovit  essential  modifications  of  the  whole  range.  That  there  were  at  the 
time,  or  at  least  had  been,  mountains  in  nearly  the  same  position  does 
not  impair  the  claim  of  this  addition  to  be  considered  as  much  a  part  of 
the  modern  Sierra  as  any  older  portion.  If  the  conclusions  thus  far  stated 
be  accepted,  it  follows  at  once  that  subsequently  to  the  close  of  the 
Knoxville,  but  long  before  the  beginning  of  the  Chico,  both  the  Sierra 
and  the  Coast  Ranges  experienced  an  upheaval.  This  was  in  all  proba- 
bility not  the  first  along  the  line  of  the  Sierra  and  very  possibly  did  not 
actually  originate  the  Coast  Ranges,  but  for  the  latter  it  is  the  first  dis- 
tinctly traceable  movement.  It  is  conceivable  that  within  the  limits  of 
time  indicated  two  upheavals  should  have  taken  place,  one  affecting  only 
the  Sierra,  the  other  only  the  Coast  Ranges;  but  the  probability  of  this 
alternative  will  scarcely  be  seriously  maintained.  The  earlier  determina- 
ble  portion  of  the  Coast  Ranges  must  therefore  be  considered  as  due  to  the 
same  disturbance  which  added  the  gold  belt  proper  to  the  Sierra  Nevada. 
There  is  much  probability  that  a  portion  at  least  of  the  Cascade  Range 
was  elevated  and  metamorphosed  at  the  same  time.  The  relationship  thus 
established  is  brought  out  more  clearly  by  a  comparison  of  the  history  of 
the  ranges  so  far  as  it  can  be  traced. 

Both  the  Sierra  Nevada  and  the  Coast  Ranges  were  above  water  and 
underwent  erosion  during  the  interval  between  the  Knoxville  and  the 
Chico  epochs.  Both  ranges  also  sank  just  before  the  beginning  of  the 
Chico,  admitting  the  ocean  over  a  great  part  of  the  Coast  Ranges  and  over 


212  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE 

considerable  areas  at  the  base  of  the  Sierra.  Both  appear  to  have  risen 
partially  and  gently  before  the  Tejon,  particularly  toward  the  north;  at  least 
the  rocks  of  this  epoch,  so  far  as  is  known,  are  confined  to  the  southern  ex- 
tremity of  the  Sierra  and  to  the  Coast  Ranges  south  of  Martinez.  A  slow 
subsidence  would  appear  to  have  taken  place  before  the  Miocene,  rocks  of 
this  age  extending  along  the  Sierra  far  to  the  north  of  the  Tcjon  localities, 
while  in  the  Coast  Ranges  they  lie  directly  upon  the  metamorphic  at  a 
great  number  of  points,  clearly  indicating  a  lower  general  level  than  dur- 
ing the  preceding  epoch.  During  the  Pliocene  very  little  of  either  range 
was  below  water. 

Not  only  was  an  important  uplift  of  the  Sierra  Nevada  contempora- 
neous with  the  first  known  upheaval  of  the  Coast  Range,  but,  even  with 
the  imperfect  information  at  command,  it  is  clear  that  the  successive  fluct- 
uations of  level  of  the  country  since  the  close  of  this  disturbance  have 
affected  these  ranges  substantially  in  the  same  manner,  and  I  cannot  but 
conclude  that  the  new  facts  brought  forward  necessitate  the  reference  of 
the  Sierra  Nevada  and  the  Coast  Ranges  to  a  single  mountain  system. 
The  Coast  Ranges  are,  and  probably  always  have  been,  of  less  altitude 
than  the  great  Sierra,  and  they  have  consequently  been  more  extensively 
immersed,  just  as  would  be  the  case  if  both  were  now  to  sink  any  given 
number  of  thousand  feet.  Between  the  Miocene  and  Pliocene  periods  the 
Coast  Ranges  also  suffered  disturbances  in  which  at  least  the  western  base 
of  the  Sierra  has  not  shared  perceptibly.  The  Sierra,  too,  has  undergone 
some  faulting  in  which  neither  the  Coast  Ranges  nor  the  basin  ranges  are 
known  to  have  shared,  but  these  differences  do  not  appear  to  me  sufficient 
to  counterbalance  the  important  coincidences  in  the  history  of  the  ranges. 

Date  of  upheaval  and  metamorphism. Tlld'C    SCCmS    eVCl'}'  rOaSOIl    tO   SUppOSG   that 

the  upheaval  of  the  Knoxville  and  Mariposa  beds  was  substantially  con- 
temporaneous with  their  metamorphism,  but  the  exact  period  at  which 
these  phenomena  took  place  is  uncertain.  That  it  was  prior  to  the  deposi- 
tion of  the  Wallala  beds,  and  therefore  before  the  Turonian,  is  indubitable. 
It  must  be  left  to  future  investigation  to  determine  whether  the  uplift  pre- 
ceded the  G-ault.  This,  however,  is  more  probable  than  the  alternative 
hypothesis,  for  tho  limited  occurrence  of  the  Hor.setown  beds  seems  to  indi- 


WALL  A  LA  BEDS.  213 

cate  that  an  uplift,  though  possibly  a  gentle  one,  occurred  between  the 
Neoconiian  and  the  Gault;  so  that,  if  it  should  prove  that  the  Horsetown 
beds  were  involved  in  the  inetamorphisin,  there  were  probably  two  distinct 
uplifts  between  the  Knoxville  and  the  WaTlala,  and  of  these  the  later  must 
have  been  much  the  more  violent.  This  appears  less  likely  than  that  a 
single  great  movement  took  place  at  the  close  of  the  period  characterized 
by  the  presence  of  Aacella  and  prior  to  the  Gault. 

The  waiiaia  series. — Along  the  coast  in  Sonoma  and  Mendocino  Counties, 
from  a  little  below  Ft.  Ross  to  beyond  the  town  of  Gualala  or  Wallala,1 
occurs  a  series  of  beds  of  very  considerable  thickness,  standing  at  a  high 
angle  and  mainly  composed  of  thick-bedded,  soft,  tawny  sandstones  ex- 
ternally similar  to  those  of  the  Chico  group  as  it  is  found  at  New  Idria 
and  elsewhere.  This  series  also  includes  large  masses  of  conglomerate, 
the  pebbles  of  which  are  chiefly  granite  and  metamorphic  rocks.  That 
these  beds  lie  unconformably  upon  the  metamorphic  has  already  been 
stated.  The  Wallala  beds  are  for  the  most  part  extremely  barren  in  fossils 
and  no  considerable  number  in  any  tolerable  state  of  preservation  were 
found  excepting  at  a  point  on  the  shore  about  a  mile  above  the  town  of 
Gualala  At  other  points  to  the  southward,  however,  fragments  of  Ino- 
ceramus,  easily  recognizable  by  the  peculiar  structure  of  the  shell,  and  a 
few  other  imperfect  fossils  were  found,  so  that  there  could  be  no  doubt  as  to 
the  faunal  continuity  of  the  beds,  even  had  the  exposure  been  less  satisfac- 
tory. 

The  National  Museum  has  also  received  from  Mr.  C.  R.  Orcutt,  of  San 
Diego,  a  few  fossils  from  Todos  Santos  Bay,  in  Lower  California,  a  part  of 
which  Dr.  White  has  determined  as  identical  with  those  from  Mendocino 
county.  He  has  described  the  following: 

Goraliiochama  Orcutti  (geu.  et  sp.  nov.). 
Trochus  curyostomus,  n.  sp.    . 
Nerita f. 

1  The  name  of  thin  town  and  of  the  river  which  thcnvempties  iuto  the  Pacific  is  variously  spelled 
Gualula,  Guadala,  Wallialla,  and  Wallala.  It  is  of  Indian  origin,  aud  the  first  form  is  an  attempt 
to  convert  it  into  Spanish.  The  third  form  is  evidently  due  to  the  resemblance  of  the  sound  to  a 
famous  mythological  name.  The  Coast  and  Geodetic  Survey,  after  careful  consideration,  have  chosen 
the  last  spelling,  which  will  no  doubt  eventually  bo  adopted  on  maps  of  the  Coast. 


214  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

Cerithiunt  Pillinyi.  u.  sp. 
Cerithhtm  totium  sanctorum,  n.  sp. 
Solarium  irallalense,  n.  sp. 

The  collection  from  Mendocino  County  included  the  first  and  the  last  of 
these  and  also  imperfect  specimens  of  an  Inoceraunis  about  a  foot  in  length, 
Ostrea,  Pcden,  and  Turritdla.  Dr.  White  believes  this  fauna  to  indicate 
the  middle  Cretaceous  and  in  some  respects  it  reminds  him  of  the  Gossau.1 

The  Wallala  beds  have  never  been  recognized  except  at  these  two 
points,  which  are  600  miles  apart.  The  northern  locality  was  manifestly 
close  to  the  shore  of  the  ocean  of  that  time,  and  the  locality  in  Lower 
California  appears  to  have  been  similar.  It  thus  seems  probable  that  the 
western  shore  of  California  was  approximately  in  its  present  position  during 
the  Turonian  epoch. 

The  chico-T  jon  series. — This  group  of  rocks  occurs  for  the  most  part  on 
the  slopes  of  the  great  valley  of  California,  the  western  side  of  the  Coast 
Ranges  being  covered  with  Wallala  beds  or  Miocene  strata  where  the  meta- 
morphic  series  is  not  exposed.  The  prevalent  rock  variety  is  sandstone  of 
medium  grain  and  usually  very  soft.3  The  lower  portion  of  the  series  is 
generally  ferruginous  and  of  a  tawny  hue,  and  spheroidal  concretions, 
though  met  in  later  sandstones,  also  are  particularly  abundant  in  the 
Chico.  The  origin  of  these  concretions  is  discussed  in  Chapter  III.  The 
upper  part  of  the  series  is  commonly  characterized  by  an  extremely  light 
color,  approaching  pure  white.  The  series  also  includes  shales,  though 
these  are  subordinate,  and  a  very  little  limestone  is  met  with  in  some 
localities,  though  not  forming  continuous  strata.  Along  the  Coast  Ranges 
the  Chico-Tojon  series  is,  so  far  as  I  know,  always  perceptibly  inclined  and 
usually  at  a  considerable  angle,  but  in  some  of  the  localities  on  the  west 
flank  of  the  Sierra  Nevada,  as  at  Chico,  the  beds  are  very  nearly  horizontal. 
Traces  only  of  cinnabar  are  known  to  occur  in  these  rocks  and  no  case  of 
metamorphism  similar  to  that  which  prevails  in  the  rocks  of  the  Knoxville 
group  has  been  observed,  though  induration  and  a  greater  or  less  impreg- 
nation with  calcite  and  gypsum  are  not  uncommon. 

1  Bull.  U.  S.  Geol.  Survey  No.  22. 

2  The  branches  of  bushes  growing  close  to  erpppings  of  these  saml.itonns  often  wear  grooves  into 
the  rock  which  are  sometimes  as  much  as  three  inches  in  depth. 


OHIOO-TfiJON  SERIES.  215 

Ne\v  Idria  affords  a  fine  exposure  of  these  rocks,  which  at  this  point 
appear  to  be  not  less  than  10,000  feet  in  thickness.  The  beds  are  tilted 
at  angles  reaching  45°  and  are  so  little  concealed  by  soil  that  a  continuous 
stratum  may  often  be  followed  for  a  considerable  distance.  There  is  no 
indication  at  this  point  of  any  break  in  the  continuity  of  deposition  of  the 
sandstones,  which  carry  a  sufficient  number  of  fossils  to  show  that  both  the 
Chico  and  the  Tejon  are  represented.  At  Mt.  Diablo,  too,  these  formations 
appear  exactly  conformable,  and,  so  far  as  is  known,  this  is  the  case  wher- 
ever they  are  found  together.  The  difference  in  color  is  the  only  physical 
peculiarity  by  means  of  which  a  division  can  be  made. 

Near  the  Vallecitos  Canon,  a  few  miles  northwest  of  New  Idria,  and 
therefore  close  to  the  locality  known  as  Griswold's  in  the  reports  of  the 
State  survey,  the  Tejon  and  Miocene  occur  near  to  each  other  and  both 
are  fossiliferous.  This  region  appeared  to  me  well  adapted  to  test  the 
question  whether  or  not  there  existed  between  the  Tejon  and  Miocene  any 
fossiliferous  strata  or  any  barren  strata  which  might  represent  an  interme- 
diate age,  for  Messrs.  Whitney  and  Gabb,  regarding  the  Tejon  as  Creta- 
ceous and  Eocene  fossils  as  absent,  believed  that  there  were  unfossiliferous 
beds  in  the  position  which  the  Eocene  should  have  occupied.  Mere  col- 
lections of  fossils  would  scarcely  be  adequate  to  determine  this  point,  and 
at  my  request  Dr.  White  examined  this  locality  with  the  special  purpose  of 
determining  the  presence  or  absence  of  an  intermediate  fauna.  He  found 
the  Miocene  and  Tejon  'conformable  here,  as  they  usually  are  elsewhere, 
and  traced  the  fossiliferous  Tejon  beds  so  close  to  the  fossiliferous  Miocene 
beds  as  to  leave  no  room  for  an  intermediate  series. 

The  age  of  the  Chico-Tejon  series  has  been  much  discussed.  Conrad 
first  determined  fossils  from  the  Tejon  which  were  collected  by  Prof.  W.  P. 
Blake  near  Ft,  Tejon.1  Of  these  specimens  Conrad  wrote:  "The  Eocene 
period  is  unequivocally  represented  by  the  beautifully  perfect  shells  from 
the  Canada  de  las  Uvas."  Either  through  a  misunderstanding  or  a  difference 
of  opinion  these  arc  referred  to  in  the  reports  of  the  State  survey  as  a  "few 
imperfect  fossils."2  Conrad  repeatedly  reasserted,  but  never  retracted,  his 

1  Pacific  Railroad  Reports,  vol.  f>,  p.  HI-1. 
i  Mul.  Survey  California,  Geology,  vol.  1,  p.  191. 


216  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

view.1  Gabb2  vigorously  maintained  the  Cretaceous  age  of  the  Ti'jon  in 
his  contributions  to  the  State  geological  reports  and  elsewhere  Prof.  J.  I). 
Dana  considers  the  Tejon  as  probably  Lower  Eocene  and  gives  a  list  of 
the  Tcjon  genera  to  show  the  Tertiary  character  of  the  fauna.3  Prof.  Jules 
Mnrcou  asserts  the  Tertiary  character  of  both  the  Chico  and  the  Ti'jon  on 
paleontologies!  and  apparently  on  lithological  grounds.4  Prof.  Angelo  Heil- 
prin,  who  has  charge  of  Gabb's  types,  has  ably  reviewed  the  Tejon  ques- 
tion and  pronounces  emphatically  for  its  Eocene  age  6  Finally,  l)r  White 
has  examined  many  of  the  principal  localities  in  the  field  and  the  collec- 
tions made  by  my  party,  as  well  as  Gabb's  types.  His  conclusion,  as  al- 
ready stated,  is  that  the  Chico  is  distinctly  Cretaceous  and  the  Tejon  dis- 
tinctly Eocene,  but  that  the  two  form  an  unbroken  series  with  a  gradual 
faunal  change. 

At  the  time  of  the  principal  controversy  on  the  subject  of  the  age  of 
the  Tejon  the  doctrine  of  evolution  had  not  permeated  science.  It  is  now 
generally  accepted  that  transitions  must  exist  between  the  faunal  groups 
or  the  geological  periods  which  have  received  distinct  names,  and  that  the 
divisions  actually  adopted  were  determined  by  the  local  conditions  of  those 
regions  in  which  geology  was  first  studied.  Twenty  years  ago  the  influ- 
ence-of  earlier  views  was  still  very  strong,  cases  of  transition  were  accepted 
with  reluctance,  and  few  doubted  that  any  series  of  beds  exhibiting  internal 
evidence  of  continuity  of  life  and  sedimentation  must  be  referred  to  a  sin- 
gle one  of  the  standard  series  of  formations,  however  remote  the  occurrence 
might  be  from  the  typical  localities  of  western  Europe.  This  feeling  was  par- 
ticularly strong  with  reference  to  the  Cretaceous  and  the  Tertiary,  between 
which,  as  everyone  knows,  there  is  a  peculiarly  sharp  break,  both  in  p]u- 
rope  and  in  the  eastern  United  States.  It  was  not  unnatural  therefore  that 
Gabb  should  deny  with  as  much  emphasis  as  italics  are  capable  of  giving 
that  the  case  in  hand  was  one  of  transition  or  that  Conrad  should  resort 

'Am.  Jour.  Conchol.,  vol.  1,  1865,  p.  362;  ibid.,  vol.  2,  180C,  p,  97;  Aui.  Jour.  Sci.,  2d  series,  vol. 
44,  1867,  p.  376. 

2  Am.  Jour.  Conchol.,  vol.  2,  1866,  p.  87;  Am.  Jour.  Sci.,  2d  scries,  vol.  44,  1867,  p.  226;  Proc. 
California  Acail.  Nat.  Sci.,  vol.  3,  1868,  p.  301.  The  last  is  the  most  elaborate. 

'Manual  of  Geology,  pp.  457,  458,  491,  508. 

'Rept,  Chief  Eng.  U.  S.  A.,  1876,  p.  387;  Bull.  Soc.  gdologique  France,  vol.  2,  1883,  p.  407. 

6Proc.  Phila.  Acad.  Sci.,  1882,  p.  195;  Contributions  to  the  Tertiary  Geology  and  Paleontology  of 
the  United  States,  1884,  p.  102. 


CIIICO-TKJUN   SERIES.  217 

to  the  hypothesis  of  fossils  washed  out  of  earlier  beds  and  redeposited  in 
younger  strata  to  account  for  the  commingling  of  Cretaceous  and  Tertiary 
types  in  the  Chico-Tejon  series.  In  correcting  their  opinions  Dr.  White 
and  I  have  simply  taken  advantage  ofJlie  advances  which  geological  sci- 
ence has  made  since  their  day. 

Dr.  White  sums  up  the  evidence  as  follows: ! 

The  Maestricht,  Faxoe,  and  other  beds  of  Europe,  although  they  are  intermediate 
between  the  Upper  Chalk  and  the  Eocene,  are  too  closely  related  by  specific  and  ge- 
neric forms  to  the  Chalk  to  be  regarded  as  separate  from  the  Cretaceous  proper.  Their 
fiiunnl  relations  to  the  Eocene  are  also  too  remote  to  allow  of  their  being  regarded  as 
in  any  proper  sense  transitional  between  the  Cretaceous  and  Tertiary.  In  Xew  Zea- 
land, however,  it  appears  probable  from  the  reports  of  the  government  geological  sur- 
veys that  there  is  in  those  great  islands  a  true  transition  from  the  Cretaceous  to  the 
Tertiary  similar  to  that  which  occurs  in  California. 

1  think  the  evidence  which  has  been  adduced  to  show  the  Eocene  age  of  the  upper 
or  Tejon  portion  of  the  Chico-Tejon  series  is  as  conclusive  as  any  evidence  of  that 
kind  can  be.  Xow,  if  we  apply  the  paleontological  standard  for  indicating  the  age  of 
formations  which  is  generally  accepted  by  geologists,  we  necessarily  refer  the  fossils 
of  the  lower  or  Chico  portion  of  that  series  to  the  Cretaceous.  The  question  then 
arises,  to  what  portion  of  the  full  Cretaceous  series,  as  it  is  recognized  in  other  parts 
of  the  world,  is  the  Chico  group  really  equivalent?  If  the  Tejou  group  is  Eocene,  it 
is  plain  that  the  Chico  group  represents  the  upper  portion  of  the  Cretaceous,  and  it 
necessarily  represents  the  very  latest  portion  of  that  period.  My  opinion,  therefore, 
is  that  it  is,  at  least  in  part,  later  than  any  formation  that  has  yet  been  referred  to  the 
Cretaceous  period  either  in  Europe  or  in  America,  and  that  it  practically  fills  the  gap 
which  is  indicated  by  *  *  *  Sir  Charles  Lyell.2 

An  examination  of  the  figures  and  descriptions  of  the  fossils  which  Mr.  Gabbhas 
referred  to  the  Chico  group,  together  with  his  catalogue  of  California  Cretaceous  fos- 
sils,3 shows  that  while  a  considerable  portion  of  them,  especially  the  Cephalopoda,  are 
of  types  which  indicate  their  Cretaceous  age.  a  large  part  of  them  are  of  genera  which 
are  known  to  range  from  the  early  Cretaceous  to  the  present  time,  and  some  of  them 
belong  to  genera  which  are  generally  accepted  as  not  older  than  the  Tertiary.  There- 
fore there,  appears  to  be  no  inherent  reason  why  this  Chico  fauna,  even  as  it  is  repre- 
sented by  Mr.  Gabb,  should  not  be  regarded  as  belonging  to  the  very  latest  portion  of 
the  Cretaceous  period.  The  fact  that  oue  or  two  Mesozoic  types  of  cephalopoda  pass 
up  from  these  strata  into  those  of  the  Tejon  portion  does  not  necessarily  prove  that  the 
latter  ought  also  to  he  referred  to  the  Cretaceous,  any  more  than  the  discovery  of  Am- 
monites in  the  Carboniferous  of  Texas  and  of  India  ought  to  require  us  to  refer  those 
strata  to  the  Mesozoic, 

1  Bull.  U.  S.  Geol.  Survey  No.  15,  pp.  16,  17. 

2  See  Lyell's  Elements  of  Geology,  1871,  p.  281. 

'  See  Geol.  Survey  California,  Paleontology,  vols.  1  and  2,  for  the  figures  and  descriptions,  and  vol. 
2,  pp.  '309-254,  for  the  catalogue. 


218  QIH'KSILVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  intimate  relation  to  each  other  of  all  the  strata  of  this  great  Chico-Tejou  se- 
ries, as  shown  by  the  mixed  character  of  its  fossils,  is  very  perplexing  when  that  con- 
dition is  considered  in  relation  to  the  established  taxonomy  of  the  formations,  but  it  is 
very  suggestive  when  considered  with  reference  to  a  search  after  the  complete  sequence 
of  geological  events.  Indeed,  such  a  condition  of  things  is  what  one  ought  to  expect 
to  find  somewhere;  but  hitherto  no  other  part  of  the  world,  if  we  except  New  Zea- 
land,has  furnished  so  strikingan  example  of  the  intimate  connection  of  two  geological 
ages,  or  at  least  of  such  connection  between  the  Cretaceous  and  the  Tertiary. 

The  Miocene. — No  sensible  non-conformity  is  known  to  exist  between  the 
Tejon  and  the  Miocene,  yet  the  distribution  of  these  two  formations 
appears  to  indicate  a  change  of  level  at  or  near  the  period  which  separates 
them,  for  the  Miocene  frequently  rests  upon  the  metamorphic  rocks  without 
the  intervention  of  other  beds  During  the  Tejon  these  areas  of  metamor- 
phic rock  must  have  been  land  and  the  subsidence  must  have  been  a 
gradual  one.  It  may  have  been  more  rapid  in  some  localities  than  in 
others,  however,  and  it  thus  appears  not  unlikely  that  an  appreciable  lack 
of  conformity  may  yet  be  detected  at  some  point  or  points  between  the 
Tejon  and  the  Miocene.1  The  Miocene  occurs  on  both  sides  of  the  Coast 
Ranges  and  on  the  lower  western  flank  of  the  Sierra.  It  is  also  abundant 
in  western  Oregon,  but  is  not  well  represented,  if  it  exists  at  all,  in  northern 
California.  It  is  composed  in  large  part  of  sandstones  somewhat  irregular 
in  texture  and  color  and  usually  distinct  from  the  earlier  rocks.  A  great 
area,  however,  is  mostly  occupied  by  extremely  fine-grained  schists. 
These  are  associated  with  bitumen  in  the  lower  counties  and  extend  up  the 
coast  to  Santa  Cruz  and  beyond.  They  are  unusually  barren  of  fossils, 
while  the  sandstones  often  contain  almost  incredible  quantities  of  shells. 
The  San  Benito  Valley  is  very  remarkable  in  this  respect. 

The  Post-Miocene  upheaval. Tll6      PlioCClie     of     tllC     CoaSt     KailgCS     is     of     VCiy 

limited  extent  and  lies,  as  Professor  Whitney  showed,  unconformably  upon 
the  Miocene,  which  is  itself  greatly  disturbed.  The  combination  of  these 
facts  shows  that  a  great  uplift  took  place  between  the  two.  As  has  been 
stated  already,  it  is  often  far  from  easy  to  distinguish  in  detail  the  effects 
of  this  upheaval  from  those  of  the  Post-Neocomian  disturbance,  audit  may 
be  added  that  still  later  uplifts  further  confuse  the  structure  of  the  Coast 

1  Since  this  memoir  was  transmitted  Mr.  J.  Marcnn  states  that  he  has  observed  such  a  want  of  con- 
formity as  is  mentioned  in  a  former  foot-note. 


THE  MIOCENE.  219 

Ranges.  In  certain  localities,  however,  as  at  New  Idria,  Mt.  Diablo,  and  the 
Blue  Range  on  Cache  Creek,  northeast  of  Knoxville,  these  effects  can  be 
somewhat  satisfactorily  compared,  and  it  then  appears  that  the  Tertiary 
upheaval,  important  as  it  was,  was  far  less  violent  than  that  which  took 
place  near  the  beginning  of  the  Cretaceous.  The  extraordinary  crushing 
so  conspicuous  in  the  Knoxville  beds,  and  in  which  an  almost  inconceivable 
amount  of  energy  must  have  been  expended,  is  not  observable  in  the  dis- 
turbed strata  of  later  age,  which,  as  a  rule,  though  inclined,  form  large 
adherent  masses  with  gentle  curves  interrupted  only  at  long  intervals  by 
faults.  The  beds  from  the  Wallala  to  the  Miocene  are  sometimes  nearly 
vertical,  but  more  generally  lie  at  an  angle  of  less  than  45°.  Along  the 
western  base  of  the  great  Sierra  the  effect  of  the  Post-Miocene  upheaval 
of  the  stratified  rocks  is,  so  far  as  I  know,  scarcely  perceptible.  It  does 
not  follow  that  it  produced  no  effect  in  this  region;  on  the  contrary,  the 
absence  of  known  Pliocene  beds  from  the  Sierra  foot-hills  seems  to  show 
that  the  range  was  raised  considerably  at  this  epoch,  though  the  energy  of 
this  movement  was  insufficient  to  produce  considerable  flexure  in  the  beds. 
At  the  eastern  side  of  the  range,  on  the  other  hand,  the  fresh-water  Truckee 
Miocene  beds  were  thrown  into  bold  folds,  their  dip  reaching  30°. l  The 
same  upheaval  was  felt  thoughout  western  Oregon,  where  it  had  the  same 
comparatively  gentle  character  as  in  the  Coast  Ranges. 

pliocene  and  Post-piiocene  strata — Pliocene  beds,  in  part  of  marine  origin,  were 
shown  by  Professor  Whitney  to  exist  at  a  number  of  points  in  the  Coast 
Ranges.  None  of  these  is  included  in  the  areas  surveyed  in  connection 
with  this  memoir.  An  interesting  fresh-water  series,  however,  occurs  to 
the  east  of  Clear  Lake,2  about  the  north  fork  of  Cache  Creek.  The  beds 
belonging  to  it  are  entitled  Cache  Lake  beds  on  the  map  of  the  region 
accompanying  this  volume.  They  are  composed  of  gravel,  sand,  and 
calcareous  beds,  partially  indurated  in  spots,  probably  by  the  action  of 
humus  acids.3  These  beds  appear  to  have  a  great  thickness  when  meas- 
ured perpendicularly  to  the  dip,  which  varies  from  10°  to  40°,  and  the  up- 

1  King:  Op.  cit.,  p.  405. 

-This  occurrence  is  referred  to  by  Professor  Whitney,  who  discovered  no  fossils  iu  it  (Auriferous 
Gravels,  p.  23). 
3  See  page  04. 


220  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE.. 

turned  edges  are  much  eroded.  They  contain  abundant  but  imperfect 
plant  remains.  Shells  are  rare,  but  were  found  at  four  localities.  These  are 
only  partially  fossilized,  but  the  larger  ones  are  compressed  and  broken  by 
the  weight  of  the  superincumbent  strata  or  by  the  movement  accompany- 
ing their  uplift,  Most  of  these  were  found  in  light-colored,  calcareous,  soft, 
and  excessively  fine-grained  material,  manifestly  a  lake  deposit. 

The  character  of  the  deposits  and  the  fact  that  the  area  occupied  by 
them  is  continuous  with  a  portion  of  Clear  Lake  led  me  to  infer  that  Cache 
Lake  might  be  regarded  as  representing  Clear  Lake  at  a  more  or  less  distant 
period.  The  recent  lake  deposits  seem  at  some  points  to  rest  immediately 
upon  those  of  Cache  Lake,  and  I  was  unable  to  see  any  distinction  between 
the  fossil  Anodonta  and  a  species  which  is  now  abundant  in  Clear  Lake 
These  facts  seemed  to  indicate  that,  in  spite  of  very  considerable  upheaval, 
there  existed  a  continuity  of  sedimentation  and  of  life  from  the  Cache  Lake 
epoch  to  the  present  The  shells  were  referred  to  Mr.  R.  E.  C.  Stearns, 
who  fully  confirmed  my  views  from  a  paleontological  standpoint,  as  the 
following  abstract  of  his  report  will  show: 

The  most  conspicuous  form  among  the  fossils  is  Anodonta  Nuttalliana 
Lea,  of  the  winged  or  connate  variety,  described  by  that  author  as  A. 
ivalilamatensis.  The  numerous  examples  of  this  shell  collected  in  the 
Cache  Lake  beds  vary  in  no  respect  from  living  specimens  readily  obtain- 
able in  the  present  lake.  The  living  specimens  from  Clear  Lake  are  also 
characteristic  and  remarkable  for  the  extreme  development  of  the  dorsal 
wing.  The  prominence  of  this  feature  Mr.  Stearns  has  observed  to  coin- 
cide with  areas  subject  to  periods  of  drought  and  severe  freshet,  It  cer- 
tainly appears  from  the  deposits  of  Cache  Lake  that  there  must  have  been 
great  periodical  variations  in  the  quantity  of  sediments  emptied  into  it,  In 
Mr.  Stearns's  opinion  this  shell  implies  that  the  character  of  the  streams 
emptying  into  Cache  Lake  was  not  markedly  different  from  that  of  the  pres- 
ent streams  of  the  same  area.  The  specimens  range  from  an  inch  (adoles- 
cent) to  over  three  and  a  half  inches  in  breadth. 

Another  shell  represented  by  numerous  specimens  from  the  Cache 
Lake  beds  is  Valvata  virens  Tryon.  This  species  was  originally  described 


FEESH-WATER  PLIOCENE.  221 

from  living  specimens  from  the  modern  Clear  Lake.  A  third  abundant 
species  is  Bythinella  intermedia  Try  on.  This  shell  is  not  known  to  exist  in 
Clear  Lake,  but  has  a  wide  distribution  on  the  Pacific  slope.  The  fauna 
of  Clear  Lake,  however,  has  not  been  systematically  investigated,  and  Mr. 
Stearns  thinks  it  by  no  means  improbable  that  B.  intermedia  still  exists  there. 
A  single  specimen,  certainly  belonging  to  the  genus  Pisidium,  and  probably 
to  the  species  abdituin  Hald.,  is  not  perfect  enough  for  specific  identification. 
There  are  several  similarly  imperfect  specimens  of  Helisoma  /  ammon  Gould 
and  an  imperfect  Pliysa,  which  is  either  P.  gyrina  or  P.  lietcrostropha.  All 
these  are  living  forms. 

The  age  of  these  beds  cannot  of  course  be  satisfactorily  determined 
from  fresh-water  shells.  The  most  careful  watch  was  kept  for  vertebrate 
remains,  but  only  a  few  fragmentary  bones  were  discovered.  These  were 
referred  to  Prof.  0.  C.  Marsh,  who  reports  finding  among  them  the  fragments 
of  a  pelvis,  apparently  of  a  horse;  the  lower  portion  of  a  scapula,  which  he 
thinks  belonged  to  a  camel;  and  the  head  of  a  large  femur,  probably  of  an 
elephant  or  a  mastodon.  These  imperfect  fossils,  he  concludes,  suggest  a 
very  late  Pliocene  age  for  the  beds  in  which  they  occur.  The  continuity 
of  life  between  Cache  Lake  and  Clear  Lake,  with  the  continuity  of  sedimen- 
tation mentioned  above,  appears  to  preclude  the  supposition  that  the  beds  are 
older  than  the  latter  part  of  the  Pliocene.  Professor  Marsh's  report  seems 
to  show  conclusively  that  they  are  not  recent,  and  that  they  must  therefore 
represent  the  close  of  the  Pliocene.  This  determination  is  of  great  impor- 
tance ;  for  it  fixes  with  accuracy  the  age  of  the  asperites  of  Clear  Lake  and, 
in  conjunction  with  other  facts,  determines  approximately  the  age  of  the 
asperites  of  Mt.  Shasta. 

Distribution  and  age  of  the  lavas. — The  region  about  Steamboat  Springs,  Nev., 
includes  the  Washoe  district,  the  eruptive  rocks  of  which  have  been  more 
extensively  discussed  than  those  of  any  other  locality  on  this  hemisphere. 
In  the  chapter  on  the  massive  rocks  it  will  be  seen  that  my  studies  of  the 
rocks  of  Steamboat  Springs  and  of  the  Washoe  district  have  led  me  to  the 
conclusion  that  the  younger  andesites  form  a  natural  group  of  trachyte  like 
rocks,  which  I  have  called  asperites.  This  same  group  is  widely  distrib- 
uted in  California.  It  forms  a  large  and  apparently  the  chief  portion  of 


222  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  material  of  Mt.  Shasta  and  the  country  surrounding  it.  Between  this 
region  and  Clear  Lake  the  country  is  practically  unknown.  At  Clear  Lake 
asperites  form  the  bulk  of  the  andesitic  eruptions.  Andesitic  areas  also 
extend  almost  uninterruptedly  in  a  southwesterly  direction  along  the  Ma- 
yacnias  Range,  including  Mt.  St.  Helena,  to  the  neighborhood  of  Vallejo,  on 
San  Pablo  Bay,  which  is  practically  the  northern  end  of  the  Bay  of  San 
Francisco.  Most  of  this  andesite  belongs  in  the  asperite  group.  Andesites 
reappear  at  Mt.  Diablo  and  to  the  eastward  of  Tres  Finos.  Comparatively 
small  amounts  of  older  dense  andesites  occur  at  Clear  Lake  and  in  the  Ma- 
yacmas  Range.  Rhyolite  in  the  areas  under  discussion  has  been  found  only 
at  New  Almaden,  but  basalt  is  widely  distributed.  It  occurs  at  Steamboat 
Springs  and  at  Washoe  and  is  abundant  near  Mt.  Shasta  and  at  Clear  Lake 
In  the  ranges  to  the  southward  of  Clear  Lake  basalt  appears  to  be  more 
widely  distributed  than  andesite,  occurring  at  Knoxville,  in  Sonoma  County 
at  the  Mt.  Fisgah  quarry,  at  Mt.  Diablo,  and  to  the  south  of  the  Bay  of  San 
Francisco  as  far  at  least  as  the  Panoche  Valley.  The  volume  of  the  basaltic 
eruptions  is  much  inferior  to  that  of  the  andesites. 

No  eruptive  rocks  of  the  Pre-Tertiary  age  are  known  to  be  intercalated 
in  the  Knoxville  or  Chico-TYjon  series  or  to  have  broken  through  them. 
The  only  earlier  eruptions  encountered  are  represented  by  pebbles  in  the 
Knoxville  and  Chico  conglomerates,  and  these  are  believed  to  have  cut 
the  granite  before  the  deposition  of  the  Knoxville  beds.  Excepting  these 
pebbles,  the  earliest  eruption  known  is  pyroxene-andesite,  which  preceded 
the  Cache  Lake  period.  Had  this  eruption  antedated  the  Miocene,  pebbles 
of  the  lava  would  almost  certainly  have  been  found  in  the  Chico-Tc'jon 
series  of  Lower  Lake.  It  may  have  accompanied  the  Post-Miocene  up- 
heaval or  it  may  have  followed  this  uplift  after  an  interval.  I  think  it 
probable  that  the  eruption  took  place  at  the  time  of  the  orographical  change 
which  dammed  bade  the  waters  of  Cache  Lake,  probably  early  in  the  Plio- 
cene or  just  before  it.  Another  outbreak  took  place  at  the  close  of  the 
Cache  Lake  period  after  an  interval  long  enough  to  permit  of  the  deposition 
of  at  least  a  thousand  feet  of  fresh-water  strata.  This  eruption,  represented 
by  the  asperites  of  Mt.  Konocti,  accompanied  an  orographical  change  which 
shifted  the  waters  of  Cache  Lake  to  the  present  Clear  Lake,  and  the  lava 


LAVAS.  223 

now  rests  in  places  upon  the  older  fresh-water  strata.  The  beds  immediately 
below  the  undesite  contain  a  few  fossil  remains  which,  as  shown  above, 
correspond  to  the  close  of  the  Pliocene.  The  Pliocene  beds  near  Mt. 
Diablo  also  contain  andesite  pebbles.  ~lrf  addition  to  the  relations  of  the 
andesites  to  the  sedimentary  rocks  at  Clear  Lake  and  Mt.  Diablo,  there  is 
some  other  evidence  bearing  upon  their  age. 

The  asperites  of  Steamboat  Springs  and  of  Washoe  show  by  the  forms 
of  their  flows,  by  the  slight  traces  of  erosion,  and  the  abundance  of  glassy 
modifications  that .  they  are  comparatively  recent.  A  comparison  of  the 
form  of  Mt.  Shasta  with  that  of  a  theoretically  perfect  volcanic  cone  shows 
that  it  is  indeed  considerably  eroded,  yet  not  so  much  so  as  to  obscure  its 
derivation  from  a  form  closely  resembling  that  deduced  from  theory.  This 
is  also  true  of  Mt,  Konocti,  on  Clear  Lake.  The  forms  of  these  cones,  as 
well  as  the  character  of  the  material  of  which  they  are  composed,  thus  show 
that  they,  too,  are  comparatively  recent.  Furthermore,  the  amount  of  de- 
parture of  these  cones  from  the  theoretical  form  is  about  the  same  for  each, 
and  so,  too,  are  the  other  evidences  of  erosion.  Hence  they  are  approxi- 
mately of  the  same  age.  From  the  relations  of  the  asperite  at  Clear  Lake 
to  the  strata,  this  age  is  known  to  be  that  of  the  end  of  the  Pliocene,  and 
Mt.  Shasta,  consequently,  also  dates  from  about  the  beginning  of  the  Qua- 
ternary. I  know  of  nothing  tending  to  prove  that  the  asperites  of  Washoe 
and  Steamboat  are  either  much  older  or  much  younger  than  the  similar 
rocks  of  the  Coast  Ranges. 

Of  the  age  of  the  rhyolite  of  New  Almaden  as  compared  with  the 
other  lavas  nothing  is  known.  It  is  clear,  however,  that  it  postdates  the 
Post-Miocene  uplift,  for,  while  the  Miocene  of  New  Almaden  is  much  dis- 
turbed, the  rhyolite  dike  intersects  the  disturbed  Miocene  and  has  itself  not 
been  affected. 

The  basalts  are  still  younger  than  the  andesites.  The  eruptions  near 
Clear  Lake  are  evidently  referable  to  a  somewhat  extended  period,  but  per- 
fect volcanic  craters  remain.  There  are  also  said  to  be  among  the  Indians 
of  the  region  traditions  of  eruptions.  In  northern  California  there  is  good 
reason  for  believing  that  there  has  been  a  small  basaltic  eruption  within 
forty  years. 


224  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

There  thus  seem  sufficient  grounds  for  asserting  that  a  more  or  less 
continuous,  but  very  irregular,  volcanic  belt  stretches  along  the  trend  of  the 
Coast  Ranges  from  Clear  Lake1  at  least  to  the  neighborhood  of  New  Idria, 
and  that  the  eruptions,  beginning  in  the  Pliocene,  extended  into  the  recent 
period  The  andesites  preceded  the  basalts  and  may  perhaps  be  consid- 
ered as  confined  to  the  Pliocene,  if  indeed  this  period  can  be  sharply  de- 
fined. There  is  considerable  reason  for  believing  that  the  andesitic  eruptions 
of  the  volcanic  belt  of  the  Coast  Ranges  are  of  pretty  nearly  the  same  age 
as  the  main  portion  of  the  similar  rocks  of  Steamboat  and  Mt.  Shasta,  and 
that  there  is  no  great  difference  in  age  between  the  basalts  of  Steamboat  and 
those  of  the  Coast  Ranges.  I  by  no  means  assert,  however,  that  the  suc- 
cessive phases  of  volcanic  activity  were  absolutely  contemporaneous  over 
the  whole  coast. 

No  uplift  which  the  Coast  Ranges  have  experienced  compares  in  vio- 
lence with  that  of  the  Post-Neocomian  epoch,  and  consequently,  whether 
the  initiation  of  volcanic  action  is  referable  to  the  very  important  Post- 
Miocene  upheaval  or  not,  it  is  a  notable  fact  that  volcanic  activity  did  not 
accompany  the  most  profound  disturbance  of  the  Pacific  Coast.  The  meta- 
morphism  of  the  rocks  at  the  period  of  the  Post-Neocomian  upheaval,  on 
the  other  hand,  seems  reasonably  ascribable  to  the  co-operation  of  the  heat 
thus  engendered. 

During  the  enormous  period  which  elapsed  from  the  close  of  the  Neo- 
comian  to  the  close  of  the  Miocene  the  erosion  was  extremely  great,  yet  no 
eruptions  took  place.  But  at  the  close  of  the  Miocene  great  masses  of  soft 
sandstones  were  elevated,  which  under  similar  meteorological  conditions 
would  be  eroded  much  more  rapidly  than  the  harder  rocks  of  the  meta- 
morphic  series.  The  conditions  in  the  Coast  Ranges  do  not,  therefore,  ex- 
clude the  hypothesis  that  the  relief  of  pressure  due  to  the  rapid  erosion  of 
these  soft  rocks  brought  about  the  fusion  of  the  lavas. 

It  is  manifest  that  the  eruptions  took  place  substantially  along  old 
belts  of  uplift  lines  of  weakness  which  are  certainly  not  younger  than  the 
Post-Neocomian  upheaval,  and,  as  I  have  pointed  out  on  a  preceding  page, 

1  Professor  Whitney's  par-lies  met  with  uo  volcanic  rocks  in  the  (.'oast   Kan^cs  iimpcr  northward 
from  Clear  Lake. 


ORE  DEPOSITS.  225 

are  probably  far  older  The  distribution  of  volcanic  rocks  in  the  belt 
where  they  occur,  however,  is  very  irregular,  corresponding  to  the  irregu- 
larity of  the  entire  chain  of  mountains  called  the  Coast  Ranges. 

A  close  connection  exists  between  the  structural  and  historical  geology 
of  the  quicksilver  belt  and  deposits  of  cinnabar,  as  will  appear  in  subse- 
quent chapters.  Here  it  is  sufficient  to  say  that  ore  deposition  has  taken 
place  only  since  the  earlier  volcanic  eruptions  and  seems  in  all  cases  to 
have  been  brought  about  by  heated  solutions  of  volcanic  origin.  Cinna- 
bar occurs  in  almost  every  variety  of  the  rocks  found  in  the  Coast  Ranges, 
and  the  age  and  origin  of  the  inclosing  rocks  do  not  seem  to  have  affected 
the  deposition  of  ore  in  any  way. 

MON   XIII 15 


APPENDIX  TO  CHAPTER  V. 

REMARKS  ON  THE  GENUS  AUCELLA,  WITH  ESPECIAL  REF- 
ERENCE TO  ITS  OCCURRENCE  IN  CALIFORNIA. 


BY  CHABLES  A.  WHITE. 


The  fossil  shells  of  the  genus  Aucella,  although  presenting  no  features  which 
especially  attract  the  attention  of  the  ordinary  observer,  have  come  to  possess 
uuusual  interest  in  certain  fields  of  paleoutological  and  geological  inquiry.  This  is 
mainly  due  to  the  constancy  of  the  distinguishing  characteristics  of  the  genus,  its 
wide  geographical  distribution,  its  restricted  range  in  geological  time,  and  the  contro- 
versy which  has  arisen  as  to  the  particular  geological  epoch  which  it  represents. 
During  the  progress  of  his  work,  the  results  of  which  are  recorded  in  this  volume, 
these  shells  have  become  of  especial  interest  to  Dr.  Becker  because  of  their  preva- 
lence in  certain  of  the  strata  with  which  he  has  had  to  deal.  I  have  therefore,  in 
compliance  with  his  request,  prepared  the  following  remarks  upon  the  genus,  its  geo- 
graphical distribution,  probable  range  in  geological  time,  and  the  variation  of  the 
forms  which  have  been  referred  to  it  under  various  specific  names. 

It  is  well  known  to  paleontologists  that  at  least  a  large  part  of  the  different 
genera  which  have  been  proposed  for  the  Aviculida1,  the  family  to  which  Aucclln  be- 
longs, are  not  so  clearly  definable  and  distinguishable  from  one  another  as  could  be 
desired,  and  also  that  the  forms  which  have  been  ranged  as  species  under  those  gen- 
era respectively  are  often  found  to  be  so  exceedingly  variable  that  it  is  difficult  to 
decide  whether  they  ought  to  be  treated  as  species  or  only  as  varieties.  While  the 
features  which  distinguish  Aucella  as  a  genus  are  not  so  conspicuous  as  those  which 
characterize  many  other  molluscan  genera,  they  have  been  found  to  be  very  constant 
in  all  the  specimens  yet  known,  even  in  cases  of  the  most  extreme  variation  in  size 
and  shape  of  the  shell.  Consequently  this  genus  has  not  been  found  to  merge  into 
related  generic  forms  by  a  modification  of  its  distinguishing  features,  as  have  some  of 
the  other  recognized  genera  of  the  Aviculida?,  and  we  may  speak  of  Aucella  as  a  genus 
with  much  more  definiteness  than  we  are  able  to  do  concerning  any  of  the  species 
which  have  been  recognized  under  it. 

The  feature  which  more  than  any  other  distinguishes  this  genus  being  the  short 
and  peculiarly  infolded  anterior  ear,  the  embedding  of  the  shells  in  the  stony  matrix 
226 


REMARKS  ON  THE  GENUS  AUCELLA.  227 

in  which  they  are  usually  found  obscures  that  feature  in  a  large  majority  of  the  speci- 
mens which  are  collected.  These  shells  iu  their  general  shape  so  much  resemble  small 
examples  of  Inoceramus  that  they  have  been  frequently  referred  to  that  genus  by 
authors  and  collectors  when  their  distinguishing  generic  features  have  been  obscured 
as  before  mentioned ;  but  when  their  full  characteristics  are  visible  tLey  are  of  course 
found  to  be  without  the  transversely  grooved  hinge  area  and  prismatic  shell  structure 
which  characterize  Inoceramus. 

The  genus  AuceUa  Las  been  recognized  in  certain  of  the  Mesozoic  rocks  of  both  the 
northern  and  southern  hemispheres,  but  its  remains' have  been  found  far  more  abun- 
dantly in  the  former  than  iu  the  latter  part  of  the  world,  and  they  seem  to  be  usually 
more  prevalent  in  high  northern  latitudes  than  farther  south.  Indeed,  so  far  as  I 
am  aware,  this  genus  has  been  recognized  at  only  two  localities  in  the  southern  hem- 
isphere, one  being  upon  the  northern  island  of  New  Zealand1  and  the  other  in  the  prov- 
ince of  Sergipe,  iu  Brazil.2  In  both  these  cases  the  recognition  of  the  genus  has  not 
been  so  complete  and  satisfactory  as  could  be  desired,  because  of  the  imperfection  of 
the  only  specimens  discovered.  Still,  there  seems  to  be  no  reason  to  doubt  the  correct- 
ness of  its  identification  in  either  case.  In  the  former  case  the  specimens  studied  by 
Professor  vou  Zittel  seem  to  have  been  few  as  well  as  imperfect  and  iu  the  latter  case 
only  two  or  three  imperfect  examples  were  discovered.  Therefore  the  following  re- 
marks will  refer  mainly  to  those  forms  which  have  been  obtained  from  the  rocks  of 
the  northern  hemisphere  and  referred  to  Aucclla  under  various  specific  names. 

The  geographical  distribution  of  Aucella  in  the  northern  hemisphere  is  circurnpolar, 
extending  far  to  the  eastward  in  certain  regions,  and  it  has  been  found  at  numerous 
localities  and  in  great  numbers.  Its  known  north  and  south  range  iu  the  northern 
hemisphere  is  from  far  within  the  Arctic  Circle  to  about  latitude  45°  in  western  Asia, 
to  southern  India,  and  nearly  to  latitude  35°  in  North  America.  It  was  first  known  in 
the  vicinity  of  Moscow,3  when  it  was  referred  to  the  genera  Inoccramus  and  ATytilus,  and 
afterward  in  Petschora  Land,4  when  Keyserling  proposed  the  generic  name  by  which 
it  is  now  known.  Subsequently  it  was  discovered  upon  the  eastern  shore  of  the  Caspian 
Sea.5  in  northern  Siberia,6  upon  Nova  Zembla,7  Spitsbergen"  and  Kuhn9  Islands  (the 
latter  lying  near  the  east  coast  of  Greenland),  in  southern  India,  as  already  mentioned,10 


'Karl  A.  Zittel:  Reise  <lcr  Ssterreichbchen  Fregatte  Novara.  Goologischer  Tlieil,  vol.  1,  part  2, 
Palaeont.,  p.  32,  PI.  VIII,  Figs.  4,  a,  b,  c. 

3  C.  A.  \Vhilr:  Conti-iljiiivoi-8  ;i  Palauontologia  do  Itra/.il  (in  both  Poi-liignoso  and  English),  Archives 
ili>  Museu  narional  ilo  KID  di'  Jam-in),  vol.  7,  p.  50,  PI.  Ill,  Figs.  11,  12,  and  13.  ' 

3  Fischer  DoWaldln- ini :   Oryetographie dn  gouvi-rm-munt  de  Mosuou,  p.  177,  PI.  XIX,  Fig.  5.  and  PI. 
XX,  Figs.  1,  •>,  and  I!. 

4  \.  Ki'ysrrling:  WUsenschaftliche  liuohachtnngmi  anfciner  Keiso  in  das  Potsuhora-Laiul,  pp.  297- 
301,  PI.  XVI,  Figs.  1-17. 

s  E.  Eichwald:  Geognoet.-palaeODt.  ISi-inerkungen  iibfr  die  Hulliinsi-1  Mangistihlak  nnd  die  aleut- 
ixclnMi  Inst-ln,  p.  53,  PI.  VI,  Figs.  10  and  11. 

'•  Middi-ndorn":  Ili-isc  in  di-n  iiiisscrsten  \orden  nnd  Oslen  Sihcrirns,  vol.  1,  \o.  1,  p.  255. 

•  S.  A.  TiilllMM-g:   Hihang  till  kongl.  svensk.  Vet.-Akad.  Hand].,  v.ii.  li,  pp.  1-2-1,  PI.  II,  Figs.  9-18. 

•G.  Lindsf  riini:  Oin  trias-  och  Jnrafdrsteningar  fran  Spetsborgon,  Kungl.  svensk. Vet.-Akad.  Haudl., 
vol.  (i,  No.  (i,  p.  M,  PI.  Ill,  Figs.  I!  and  I. 

v  F.  Toula:  Die  zwi-id-  dcutache  Nordpolarfahrt,  vol.  2,  pp.  497-505;  also,  Feikleu  and  de  Ranee: 
Quart.  Jour.  Ci-ol.  Sor.  London,  vol.  34,  1876,  p.  56. 

10 F.  Stoliczka:  Pal.  ludica,  vol.  3,  p.  404,  PI.  XXIII. 


228  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

in  Alaska,1  British  America,2  and  iu  various  parts  of  California.3  In  the,  latter  region 
the  first-discovered  examples  were  referred  to  the  genera  Inoceramm  and  Lima,  re- 
spectively, and  their  relation  to  the  Aucellax  of  the  eastern  hemisphere  was  not  then 
suspected. 

Shells  of  this  genus  have  been  found  at  various  other  localities  and  have  been 
referred  to  by  various  authors  in  their  publications,  but  the  foregoing  references  are 
sufficient  to  indicate  the  wide  geographical  and  the  interesting  circutnpohir  range  of 
the  genus. 

While  the  distinguishing  generic  features  of  the  shells  which  have  been  found  at 
all  these  widely  separated  localities  in  the  northern  hemisphere  are  constant,  the  range 
of  variation  in  subordinate  features,  especially  size  and  shape,  is  so  great  that  no  less 
than  nine  specific  and  several  varietal  names  have  been  proposed  by  different  authors 
who  have  studied  them.  Tue  figures  on  the  accompanying  plates  have  been  prepared 
to  show  the  extremes  of  the  variations  which  have  been  observed  and  to  illustrate  the 
principal  forms  respectively  which  have  been  selected  as  types  of  the  proposed  species. 
If  only  those  forms  to  which  the  respective  specific  names  have  been  applied  had  ever 
been  known,  the  real  specific  identity  of  each  might  not  have  been  questioned.  For- 
tunately, however,  Aucella  having  been  a  gregarious  inolhisk,  great  numbers  of  speci- 
mens have  usually  been  found  wherever  any  have  been  discovered,  except  at  the  New 
Zealand,  Brazilian,  and  Indian  localities.  Consequently,  so  large  a  number  of  inter- 
mediate varietal  forms  have  been  found  that  I  do  not  hesitate  to  express  the  opinion 
that  none  of  the  proposed  species  can  be  clearly  diagnosed  from  the  others,  nor  to  treat 
as  a  specific  unit  all  the  forms  referred  to,  with  perhaps  the  exception  of  the  Indian, 
Brazilian,  and  New  Zealand  examples. 

It  frequently  happens  that  all  or  the  greater  part  of  the  specimens  found  com- 
mingled in  any  given  layer  agree  closely  with  some  one  of  the  recognized  specific 
forms  ;  and  it  is  also  true  that  two  or  three  of  those  forms  aiv  often  found  commingled 
in  one  and  the  same  layer.  It  thus  often  happens  that  a  collection  of  these  shells 
made  at  one  locality  or  in  one  neighborhood  is  found  to  contain  representatives  of  more 
than  one,  and  sometimes  of  the  greater  part,  of  the  forms  which  have  been  recognized 
as  species  by  different  authors.  These  representative  forms  have  usually  been  selected 
by  authors  lor  reference  and  illustration,  while  little  mention  has  been  made  of  the 
intermediate  forms.  That  the  foregoing  statement  is  correct  appears  from  the  pub- 
lications of  the  various  authors  referred  to,  and  it  also  accords  with  my  own  obser- 
vations upon  the  collections  that  have  been  made  in  North  America. 

In  view  of  the  facts  just  stated,  the  conclusion  seems  to  be  necessary  that  all  the 
forms  of  Aucella  which  have  yet  been  discovered,  especially  those  of  the  northern  hem- 
isphere, have  so  close  a  genetic  relationship  with  one  another  as  to  hardly  exceed  the 


1  E.  Eichwalil:  Geognost.-palaeont.  Boiuerkuugcn  liber  die  Halbinsel  Mangischhik  mill  die  aleut- 
ischeu  Inseln,  pp.  185-187,  PI.  XVII,  Figs.  1-17;  P.  Fischer:  Voyage  alac6tonord-ouestdt<  I'Ame'rique, 
par  M.  Alph.  Pinart,  pp.  33,  PI.  A,  Figs.  4  and  5;  C.  A.  White:  Hull.  U.  S.  Geol.  Survey  No.  4,  pp.  10- 
14,  PI.  VI,  Figs.  2-12. 

'2J.  F.  Whiteaves:   Proc.  Trans.  Royal  Soc.  Canada,  vol.  1,  1883,  p.  84. 

3W.  M.  Gubb:  Geol.  Survey  California,  Paleontology,  vol.  1,  18(!4,  p.  187,  PI  XXV,  Fig.  173; 
ibid.,  vol.  2,  1868,  p.  194,  PI.  XXXI,  Fig.  92;  Proc.  California  Acad.  Nat.  Sci.,  vol.  3,  1885,  p.  173;  F.  B. 
Meek:  Geol.  Survey  California,  Geology,  vol.  1,  1865,  p.  479,  PI.  I,  Figs.  1-5;  C.  A.  White:  Hull.  U.  S. 
Geol.  Survey  No.  15;  G.  F.  Becker:  Bull,  U.  S.  Geol.  Survey  No,  19. 


REMARKS  ON  THE  GENUS  AUCELLA.  229 

limits  which  may  be  reasonably  assumed  as  those  of  a  single  species.  Professor  von 
Zittel  recognized  the  close  relationship  of  the  New  Zealand  form  with  A.  concentrica, 
1  found  the  Brazilian  form  to  differ  from  the  latter  in  hardly  a  greater  degree,  and 
Stoliczka's  Indian  species  is  evidently  closely  like  certain  varieties  of  A.  concentrica. 
It  may  be,  therefore,  that  we  ought  to  regard-  this  relationship  as  extending  to  the 
Aiicellas  of  the  southern  hemisphere  and  possibly  also  to  the  Indian  form,  although 
the  latter  comes  from  strata  which  we  seem  bound  to  regard  as  of  considerably  later 
age  than  the  others. 

Admitting  this  close  genetic  relationship  of  all  the  known  forms  of  Aucella,  it  is 
necessary  to  further  conclude  that  they  have  beeu  dispersed  from  some  geographical 
center.  The  only  published  reference  to  such  dispersion  that  has  come  to  my  notice  is 
a  brief  suggestion  by  Mr.  A.  Pavlow  that  in  Russia  they  were  derived  from  the  north,1 
but  this  does  not  fully  meet  the  broader  question  of  circumpolar  and  still  more  extensive 
distribution. 

Having  been  dispersed  from  a  single  geographical  center,  the  strata  which  bear 
the  remains  of  the  original  colony  are  necessarily  older  than  those  which  bear  the  re-' 
in  lins  of  the  colonies  which  were  last  established  before  the  extinction  of  the  genus  to 
the  extent  of  the  time  which  was  occupied  by  the  dispersion  and  colonization.  If, 
therefore,  the  dispersion  was  primarily  from  the  north,  the  northern  Aucella-benriug 
strata  are  necessarily  older  than  the  more  southerly  ones,  and,  if  subsequent  dispersion 
was  from  the  eastern  to  the  western  hemisphere,  the  eastern  strata  referred  to  are  neces- 
sarily older  than  the  western.  I  think  our  present  knowledgeof  this  subject  is  too  meager 
to  warrant  any  definite  statement  as  to  the  directions  in  which  dispersion  has  occurred: 
but  the  geographical  distribution  of  this  assumed  single  species  is  so  extremely  wide 
and  its  climatic  range  has  been  so  very  great  that  the  time  required  for  its  dispersion 
may  easily  have  extended  from  the  closing  epoch  of  the  Jurassic  into  the  Neocomian 
epoch  of  the  <  'retaceous,  and  there  are  apparently  good  reasons  for  believing  that  such 
was  really  the  case. 

The  genus  Aucella  has  beeu  regarded  by  the  majority  of  authors  who  have  written 
upon  it  as  diagnostic  of  the  Jurassic  age  of  the  strata  which  bear  it;  but  certain 
authors  whose  opinions  are  worthy  of  consideration  are  equally  confident  that  all  such 
strata  should  be.  regarded  as  of  Neocomian  age.  Professor  vou  Zittel  refers  his  A. 
plictitit  from  Xew  Zealand  to  the  "Jura  or  Lower  Cretaceous."  The  form  described 
by  me  (op.  cit.)  from  the  province  of  Sergipe,  Brazil,  under  the  name  of  A.  Irazilien  is, 
is  from  strata  that  I  have  referred  to  the  Xeocomian  and  there  seems  to  be  no  possible 
reason  to  question  the  Cretaceous  age  of  the  Indian  species  described  by  Stoliczka. 
It  is  Profosor  Eichwald  more  especially  who  has  contended  for  the  Neocomian  age  of 
the  .1  Ht-illit -bearing  strata  of  Europe  and  northern  Asia,  and  he  also  makes  the  same 
claim  for  those  of  Alaska.  Mr.  Whiteaves  (op.  cit.)  is  equally  confident  of  the  Cre- 
taceous age  of  the  Ana  //((bearing  strata  of  British  Columbia.  In  California,  although 
a  part  of  the  strata  which  bear  A  ncr.Ua  have  been  referred  to  the  Jurassic,  those  which 
bi-ar  these  shells  most  abundantly  have  been  referred  by  all  the  geologists  who  have 
studied  them  to  the  Shasta  group  of  the  Cretaceous  series,  and  there  seems  to  be  no 
good  reason  to  doubt  the  correctness  of  that  reference. 


1  Bull.  Soc.  g£olngii[iie  France,  :iil  series,  vol.  12,  1S84,  pp.  GS<i-(i%. 


230  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

We  do  not  yet  know  enough  of  the  general  geology  of  Alaska  to  speak  confidently 
of  the  stratigraphical  relations  of  the  Aucella  bearing  strata  there;  but  there  seems 
now  to  bo  no  reason  to  doubt  that  all  such  strata  in  other  parts  of  western  North 
America  ought  to  be  referred  to  the  opening  epoch  of  the  Cretaceous.  I  do  not  think, 
however,  that  the  question  of  the  exact  geological  age  of  these  strata  is  of  great  im- 
portance in  this  connection,  but  no  reasonable  doubt  can  be  entertained  that  a  large 
proportion  of  the  discoveries  of  Aucella  have  been  made  in  strata  of  unquestionably 
Cretaceous  age. 

In  the  year  1864  Mr.  William  M.  Gabb  published  specimens  of  Aucella  from  two 
separate  localities  in  California  and.  as  was  then  supposed,  from  two  separate  forma 
tions.  The  first  of  these  was  published  under  the  name  of  Inoceramus  Piochii1  and 
the  other  under  the  name  of  Lima  Erringtonii.'1  The  first-mentioned  fossils  were 
afterward  published  by  him  as  Aucella  PiocMi,3  and  Mr.  Meek  afterward  republished 
and  illustrated  the  others  under  the  name  of  Aucella  Erringtonii.4  Mr.  Gabb  never 
doubted  the  Cretaceous  age  of  the  first-mentioned  forms;  but  it  seems  that  he 
regarded  the  strata  from  which  came  his  Lima  Erringtonii  as  of  Jurassic  age.  Mr. 
Meek  agreed  with  him  in  this  respect,  as  did  also  other  authors. 

Upon  an  examination  of  the  collections  made  in  California  by  the  division  of  the 
U.  S.  Geological  Survey  in  charge  of  Dr.  Becker,  which  were  submitted  to  me  in  1884, 
I  became  satisfied  that  the  Aucella  PiocMi  and  A.  Erringtonii  of  Gabb  belong  to  one 
and  the  same  species  and  that  that  species  was  no  other  than  the  one  which  had  long 
been  known  under  the  various  names  of  A.  concentrica,  A.  monquensis,  A.  pallasii,  A. 
crassicollis,  etc.  (see  Bull.  U.  S.  Geol.  Survey  No.  15,  p.  23). 

As  Aucella  Erringtonii  was  obtained  from  the  auriferous  slate  series  in  California, 
this  conclusion  of  course  involved  the  opinion  that  at  least  a  part  of  that  series  is 
equivalent  to  the  Knoxville  division  of  the  Shasta  group,  and  therefore  of  Creta- 
ceous age.  This  conclusion  was  supported  by  the  personal  discovery  in  the  auriferous 
slates  of  the  Mariposa  estate,  in  company  with  Dr.  Becker  and  his  assistant,  Mr.  Turner, 
of  specimens  of  Aucella  that  are  plainly  identical  with  the  A.  PiocMi  of  Gabb,  which  is 
found  abundantly  in  the  Knoxville  division  of  the  Shasta  group.  These  and  other  facts 
bearing  upon  the  relations  of  the  Aucella-Vtearing  strata  of  different  districts  in  Cali- 
fornia are  discussed  by  myself  in  Bulletin  No.  15  of  the  U.  S.  Geological  Survey  nnd 
by  Dr.  Becker  in  Bulletin  No.  19.  So  far  as  I  am  aware,  no  other  forms  than  those 
mentioned  in  this  article  are  properly  referable  to  the  genus  Aucrlia.  It  is  plain  that 
neither  the  A.  contracta  nor  the  A.  impressa  of  Quenstedt  belongs  to  this  genus.6  It  is 
also  evident  that  the  greater  part  of  the  species  which  Stoliczka  ranged  under  the 
genus  Aucella  were  not  intentionally  so  placed  by  him.6 

EXPLANATION  OF  THE  PLATES  AND  COMMENTS. 

In  the  foregoing  paragraphs  I  have  expressed  serious  doubt  whether  more  than 
one  clearly  definable  species  of  Aucella  is  yet  known,  at  least  in  the  northern  hemi- 

1  Geol.  Survey  California,  Paleontology,  vol.  1,  lrif>4,  p.  187,  PI.  25,  Figs.  173,  174. 

2  Proc.  California  Acad.  Nat.  Sci.,  vol.  3,  1868,  p.  173. 

3  Geol.  Survey  California,  Paleontology,  vol.  2,  ItW,  p.  191,  PI.  32,  Fig.  92,  a,  l>,  c. 
'Geol.  Survey  California,  Geology,  vol.  1,  1865,  pp.  479,  480,  PI.  I,  Figs.  1,2,3,  4,  and  5. 
'•  ]>cr  Jura,  p.  501,  PI.  f.7.  Fig.  2,  and  p.  582,  PI.  73,  Fig.  47. 

"Pal.  Imlica,  vol.  3,  index,  p.  513. 


0»  THU 

UNI7ERSIT7 


U.  a.  GEOLOGICAL  SURVEY 


MONOGRAPH  XIII     PL  -III 


1 

EUROPEAN  AND  OTHER  FOREIGN  FORMS  OF  AUCELLA. 


REMARKS  ON  THE  GENUS  AUCELLA.  231 

sphere,  with  perhaps  the  exceptiou  of  the  species  from  southern  ludia.  If  that  view 
is  to  be  accepted  without  qualification,  some  one  only  of  the  various  names  which  have 
been  proposed  must  be  selected  to  designate  that  widely  variable  species.  A  common 
custom  among  naturalists  in  such  cases  is  to  take  the  specific  name  first  used  or  pro- 
posed by  the  author  of  the  genus,  which  is  finally  recognized  as  the  true  one.  But  I  do 
not  think  the  judgment  of  subsequent  naturalists  who  have  availed  themselves  of  con- 
stantly increasing  knowledge  should  always  be  hampered  by  rigid  rules  of  this  kind 
I  have  therefore  selected  the  specific  name  concentrica  to  be  used  in  ordinary  cases, 
because  the  form  to  which  that  name  is  applied  appears  to  have  been  the  first  one  dis- 
covered and  also  because  it  is  more  generally  prevalent  than  the  one  to  which  Keyserling 
gave  the  name  pallasii,  although  he  placed  the  latter  name  first  under  the  genus  Aucclla. 
But  in  referring  now  to  the  various  forms  here  illustrated  I  shall  use  the  names  which 
the  different  authors  have  applied  to  them. 

The  figures  on  PI.  Ill  are  mostly  copies  of  those  which  represent  the  different 
forms  that  have  been  recognized  in  Europe,  together  with  those  fcorn  southern  India, 
New  Zealand,  and  Brazil.  Those  upon  PI.  IV  represent  North  American  forms,  a  part 
of  them  being  copies  of  figures  previously  published  and  a  part  having  been  prepared 
for  this  occasion. 

PLATE   III. 

FIG.  1.  A  copy  of  Keyset-ling's  figure  of  Amelia  concentrica,  from  Reise  in  das  Petschora-Land,  PI. 
XVI,  Fig.  16. 

FIGS.  2  and  3.  Copies  of  Keyserling's  figures  (loe.  cit.,  Figs.  13  and  14),  representing  A.  concentrica 
var.  sublturis. 

FIGS.  4  and  5.  Copies  of  Keyserling's  figures  of  A.  crassicollis  (loc.  cit.,  Figs.  9  and  11). 

FIGS.  6,  7,  and  8.  Copies  of  Tullberg's  figures  of  A.  mosijuensis,  from  Nova  Zembla  (Biliaug  till 
kongl.  svensk.  Vet.  Akad.  Handl.,  vol.  6,  PI.  II,  Figs.  10,  17,  and  18).  These  figures  are  regarded  by 
Tullberg  as  representing  the  form  which  Koyserling  gave  as  the  type  of  A.  mosqitensis.  Keyserliug  fig- 
ured only  the  right  valve  of  one  example,  and,  as  the  left  valve  was  not  illustrated,  several  anlhors  be- 
sides myself  have  hitherto  regarded  A.  mosquensls  as  having  a  more  elongate  form.  Specimens  having 
the  beak  of  the  left  valve  so  short  and  so  slightly  prominent  as  is  shown  by  Tullberg's  figures  have  not 
often  been  observed  in  North  American  strata. 

FIG.  9.  A  copy  of  one  of  Keyserliug's  original  figures  of  his  A.  pallaiii  (loc.  cit.,  Fig.  4).  The  ra- 
diating linos  shown  ou  this  figure  are  often,  but  not  always,  observable  on  this  form.  They  are  some- 
times observable  on  the  other  forms,  but  are  more  often  absent. 

FIGS.  10  and  11.  Opposite  views  of  a  specimen  in  the  U.  S.  National  Museum  from  the  vicinity  of 
Moscow.  It  appears  to  belong  to  the  form  A.  pallasii. 

FIGS.  12  ami  13.  Opposite  views  of  another  example  from  near  Moscow,  presented  to  Dr.  Becker 
by  Professor  Holzapfel.  It  may  perhaps  be  regarded  as  a  variety  of  A.  pallasii,  although  some  authors 
would  probably  regard  it  as  quite  as  near  to  A.  moK<]iifiifin.  This  uncertainty  of  specific  recognition 
l>y  different  authors  is  of  itself  an  indication  of  the  instability  of  all  the  forms  which  have  been  des- 
ignated as  species. 

FIGS.  14,  15,  and  1C.  Copies  of  Professor  von  Zittel's  figures  of  his  A.  plicata  from  New  Zealand 
(Reise  der  osterreichischon  Fregatte  Novara,  Geol.  Theil,  vol.  1,  part  2,  Paleont.,  p.  32,  PJ.  VIII, 
Figs.  4,  a,  b,  c). 

FIGS.  17  and  18.  Copies  of  original  figures  of  A.  Iraziliensit  White  (Contribuicoes  a  Palaeontologia 
do  Brazil,  Archives  Mnseu  nac.  do  Rio  de  Janeiro,  vol.  7).  The  narrow,  rough  seam  along  the  middle 
of  the  figure  is  a  mineral  vein,  and  not  a  natural  feature  of  the  shell. 

I'n.s.  19  and  20.  Copies  of  Stoliczka's  figures  of  his  A.  parva  (Pal.  Indica,  vol.  3,  PI.  XXXIII, 
Figs.  2a  and  3). 

PLATE   IV. 

FIGS.  1  and  2.  Copies  of  Gabb's  original  figures  of  his  Inoceramut  [Aucella]  Piochii  (Geol.  Survey, 
California,  Paheontology,  vol.  1,  PI.  XXV,  Figs.  173  and  174). 


232  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

FIGS.  :i,  4,  and  5.  Copies  of  Gabb's  subsequent  figures  of  Aucrlla  1'iocliii  (Gcol.  Survey  California, 
Paleontology,  vol.  2,  PI.  XXXII,  Figs.  92,  92<i,  and  92ft). 

FIGS.  6,  7,  8,  9,  and  10.  Copies  of  Meek's  figures  of  Aucella  Ernngtoiiii  (Lima  Erringtonil  Gabb) 
(Geol.  Survey  California,  Geology,  vol.  1,  Figs.  1,  la,  2,  2a,  and  5e).  The  radiating  Hues  shown  ontluse 
specimens  seem  to  have  been  somewhat  exaggerated  by  lateral  pressure. 

FIGS.  11,  12,  13,  14,  and  15.  Copies  of  the  author's  figures  of  specimens  from  Alaska,  published  in 
Bull.  U.  8.  Geol.  Survey  No.  4,  PI.  VI,  Figs.  2,  3,  8,  9,  and  10. 

FIGS.  1C  a4id  17.  Two  views  of  a  remarkably  ventricose  left  valve  from  the  Kuoxville  division  of 
the  Shasta  group  near  Kuoxville,  Cal. 

FIGS.  18  and  19.  Lateral  views  of  two  left  valvf s  from  the  Kuoxville  division  of  the  Shasta  group 
near  Kuoxville,  Cal.  These  examples  have  suffered  no  lateral  pressure,  but  the  radiating  lines  have 
been  made  a  little  too  distinct  by  the  artist. 

FIG.  20.  A  right  valve  from  the  same  locality. 

FIG.  21.  A  left  valve  from  Washington  Territory,  collected  by  Prof.  Thomas  Condon. 

These  figures  of  North  American  specimens  of  Aucella  show,  if  possible,  a  greater 
range  of  variation  than  do  the  figures  given  on  PI.  III.  The  forms  known  by  the 
specific  names  of  voncentrica,  paUasii,  and  cratsicollis,  respectively,  are  readily  recog- 
nizable among  these  figures  of  American  Aucellas.  There  is,  however,  one  form 
among  them  which  has  apparently  not  been  recognized  outside  the  limits  of  North 
America,  and  yet  it  is  probable  that  it  exists  elsewhere.  Figs.  10  and  17  represent 
an  extreme  example  of  this  form  or  variety  from  California  and  Figs.  14  and  15  repre. 
sent  a  less  pronounced  example  from  Alaska.  On  the  other  hand,  the  form  which 
Tullberg  figures  as  A.  mosquenais,  of  which  Figs.  6,  7,  and  8,  PI.  Ill,  are  copies, 
does  not  appear  among  the  North  American  forms  which  are  here  figured,  and  it  is 
probably  rare  in  North  American  strata. 

Figs.  4,  13,  and  21  may  be  taken  as  representatives  of  the  form  A.  crassicollis, 
and  yet  in  each  case  the  specimens  represented  by  these  figures  were  found  com- 
mingled and  embedded  with  other  forms.  Figs.  6,  7,  8,  9,  and  10  are  apparently 
referable  to  the  form  A.  pallasii,  as  represented  by  Fig.  9,  on  PI.  III.  Figs.  18,  19, 
and  20  ought  probably  to  be  regarded  as  varieties  of  that  form,  although  there  seems 
to  be  quite  as  much  reason  for  referring  them  to  A.  mosquensis. 

The  radiating  lines  which  appear  upon  some  of  these  figures,  as  well  as  those  of 
some  European  examples,  are  oftener  seen  upon  the  form  A.  pallasii  than  upon  the 
other  forms;  but  such  markings  are  not  exclusively  confined  to  any  one  form.  There 
is  also  much  difference  observable  in  the  strength  of  the  concentric  markings  of  all 
the  forms;  but  this  cannot  be  regarded  as  even  a  varietal  character.  Many  of  the 
specimens  appear  unnaturally  smooth,  because  of  the  fact  that  a  large  part  of  the 
examples  discovered  are  casts  of  the  interior  of  the  shell,  the  test  itself  having  been 
destroyed  or  removed. 


D.  B.  UEOL03ICAL  SDEVEY 


MONOGRAPH  XIII    PL.  17 


AMERICAN    FORMS    OF    AUCELLA 


CHAPTER  VI. 

DESCRIPTIVE  GEOLOGY  OF  THE  CLEAR  LAKE  REGION. 

[Atlas  Sheet  III.] 

General  character.  —  Clear  Lake  is  an  irregular  and  picturesque  sheet  of 
water,  lying  at  an  elevation  of  1,310  feet1  in  the  heart  of  the  Coast  Ranges. 
Many  of  the  surrounding  hills  rise  to  an  elevation  of  about  one  thousand 
feet  above  the  level  of  the  lake,  but  the  dominant  feature  of  the  scenery 
is  the  prominent  mass  of  Konocti  (or  Uncle  Sam),  the  summit  of  which,  as 
measured  by  Mr.  J.  D.  Hoffmann,  stands  2,936  feet  above  the  lake  at  high 
water  (March,  lcS84).  Konocti  is  a  group  of  volcanic  cones  considerably 
eroded,  but  retaining  clear  traces  of  its  original  form,  to  which  it  approxi- 
mates as  nearly  as  do  Mt.  Shasta  and  Mt.  Hood.2  Like  those  mountains, 
too,  it  is  composed  of  andesites  of  the  group  called  asperites  in  a  preceding 
chapter  and  is  probably  of  very  nearly  the  same  age.  The  peaks  »are 
rocky  and  the  declivity  toward  the  remarkable  basin  of  Little  Borax  Lake 
is  precipitous.  The  eastern  flank  also  is  steep  and  the  rock  is  exposed  to 
view  over  a  wide  area.  Here  it  is  scored  with  three  sets  of  concentric  linos, 
which  sweep  across  the  mountain  side  in  graceful  curves  and  mark  series 
of  bedded  Hows  of  the  lava  composing  the  mass.  The  lower  portions  of 
Konocti  and  a  very  large  proportion  of  the  ranges  of  the  district  are 
densely  clothed  with  brush,  chiefly  dwarf  oaks,  chamisal,  and  manzanita. 
These  remain  green  throughout  the  summer  and  mitigate  the  impression  of 
drought  which  the  scenery  in  general  creates.  They  also  afford  a  refuge 


Uy  Mr.  K.  K.  Nichols  for  the  Clear  Lake  Water  Company. 

my  paper  "Oil  the  geometrical  form  of  volcanic  cones,"  Am,  Jonr.  Sci.,  3d  series,  vol.  30,  1885, 
p.  ',Kt. 

233 


234  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

for  numerous  deer  and  other  wild  animals,  but  neither  the  topographer  nor 
the  geologist  can  contemplate  these  smooth,  green  surfaces  with  any  sat- 
isfaction, for  the  brush  is  often  impenetrable  for  men  or  horses,  while  the 
matted  roots  and  accumulated  mold  seldom  allow  an  inspection  of  the 
underlying  rock.  The  growth  of  the  brush  seems  capricious  and  is  not 
altogether  dependent  on  either  the  exposure  or  the  soil,  for  often  a  portion 
of  a  slope  is  densely  covered  with  brush  while  the  remainder  is  wholly  free 
from  it.  The  distribution,  however,  is  probably  governed  to  a  great  extent 
by  the  amount  of  moisture,  for  the  southern  exposures  are  much  less  often 
obstructed  than  the  northern  ones.  The  valleys,  on  the  other  hand,  are 
usually  free  from  brush  and,  like  a  portion  of  the  hills,  are  studded  with 
fine  oaks,  growing  as  a  rule  at  distances  of  one  or  two  hundred  feet  from 
one  another  and  often  as  picturesquely  disposed  as  if  set  out  by  a  skillful 
landscape  gardener. 

This  portion  of  California  is  full  of  mineral  springs,  and  Clear  Lake 
possesses  its  share,  of  which  the  warm  chalybeate  rising  through  the  waters 
of  the  lake  at  Soda  Bay  is  the  best  known  and,  with  the  charms  of  scenery, 
yearly  attracts  a  number  of  visitors.  Of  more  scientific  interest  are  the 
two  borax  lakes — pools  without  outlets — in  which  borax  has  concentrated 
and  accumulated  to  such  an  extent  as  to  have  yielded  a  large  quantity  of  this 
salt  to  commerce.  But  by  far  the  most  remarkable  locality  in  the  region 
is  the  Sulphur  Bank,  where  extremely  hot  springs  and  large  accumulations 
of  native  sulphur  were  long  ago  known  to  exist.  When  this  sulphur  came 
to  be  exploited  it  was  found  that  underlying  and  in  part  mingled  with  it 
there  were  large  quantities  of  cinnabar.  As  may  be  seen  from  Chapter  I, 
the  production  of  quicksilver  at  this  locality  has  reached  a  large  total, 
though  it  has  not  proved  the  almost  inexhaustible  source  of  supply  it  was 
once  supposed  to  be. 

Geoiogica;  map. — The  Sulphur  Bank  lies  at  the  extreme  northwest  limit  of 
the  area  investigated  by  Professor  Whitney  and  his  assistants,  and  its  gen- 
eral geological  relations  were  so  little  known  at  the  time  when  this  investi- 
gation was  undertaken  that  it  was  found  indispensable  to  a  clear  understand- 
ing of  the  occurrence  of  ore  to  submit  a  district  of  considerable  size  to  ex- 
amination. The  oldest  rocks  in  the  neighborhood  of  Clear  Lake  belong  to 


MAP  OF  CLEAR  LAKE.  235 

the  Knoxvillc  group.  They  occupy  the  greater  portion  of  the  surface  and 
are  in  great  part  highly  plicated  and  metamorphosed  or  silicified.  On  this 
foundation  rest  Chico-Tejon  beds,  Pliocene  strata,  and  volcanic  rocks,  with 
the  last  of  which  are  associated  the  qurrlcsilver  deposits. 

The  distribution  of  the  rocks  is  shown  on  the  reconnaissance  map 
(Atlas  Sheet  III).  The  topography  of  this  map  was  not  prepared  for  the 
Survey,  the  necessity  for  the  examination  of  so  large  an  area  not  having 
been  apparent  until  the  detailed  examination  of  the  Sulphur  Bank  had 
begun.  It  was  compiled  by  Mr.  C.  F.  Hoffmann  from  the  published  work 
of  the  former  State  geological  survey,  from  plats  in  the  surveyor  general's 
office,  private  surveys  by  Mr.  R.  K.  Nichols,  of  Lower  Lake,  the  detailed  map 
of  Sulphur  Bank  prepared  for  this  volume,  private  notes  of  the  compiler, 
and  a  little  supplementary  work  by  Mr.  J.  D.  Hoffmann.  While  it  makes 
no  pretension  to  the  detailed  accuracy  of  the  special  maps  prepared  by  the 
geographical  division  of  the  Survey,  it  represents  the  country  fairly  well, 
perhaps  as  accurately  as  the  present  needs  of  this  section  of  the  State  de- 
mand. The  geology  is  represented  upon  it  as  minutely  as  the  character  of 
the  map  will  permit,  preference  of  course  being  given  to  the  indications  of 
the  topography  rather  than  to  the  bearings  of  known  points  wherever  there 
was  a  slight,  discrepancy.  The  data  are  on  record  for  still  more  accurate 
plotting,  should  the  preparation  of  a  detailed  map  ever  be  undertaken. 

The  Knoxviiie  series —  Xo  fossils  of  the  Knoxville  group  were  discovered  in 
the  immediate  vicinity  of  Clear  Lake,  but  the  series  was  followed  almost 
without  a  break  to  the  Manzanita  mine  on  Sulphur  Creek,  Colusa  County, 
where  AurrJIn  ri/in-i'/tfi/cri  and  RliyiichoneUa  Wliitneyi  are  abundant.  The 
lithological  character  of  the  altered  rock  of  Clear  Lake,  its  structural  pecu- 
liarities, and  its  relation  to  the  Chico-Tijon  series,  when  compared  with 
those  of  fossiliferous  occurrences  elsewhere,  all  indicate  beyond  any  rea- 
sonable doubt  that  it  belongs  to  the  Knoxville  group. 

The  Knoxville  beds  of  the  Clear  Lake  region  have  undergone  very 
violent  disturbances.  A  great  deal  of  time  and  pains  were  spent  in  a  sys- 
tematic investigation  of  the  dips  of  these  rocks  in  the  area  shown  on  the 
map  of  Sulphur  Bank  for  the  purpose  of  constructing  sections,  but  this  was 
found  wholly  impossible.  The  entire  mass  has  been  shattered,  and  the 


236 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


blocks  are  very  frequently  so  displaced  that  there  is  an  utter  discordance 
between  the  various  dips  observable  in  a  single  cropping  of  a  few  feet  in 
diameter.  That  there  may  be  predominant  faults  (DaubreVs  paraclases),  as 
well  as  the  innumerable  piesoclastic  fissures,  is  not  improbable  ;  but  between 
the  extreme  disturbance  shown  by  the  exposed  rock  and  the  proportion  of 
the  surface  covered  by  soil  this  could  not  be  determined.  Only  one  result 
was  obtained  by  the  study  of  dips.  This  is,  that  the  ridges  are  mainly 
synclinal  folds,  so  that  the  prevalent  dip  of  the  Knoxville  beds  is  into  the 
hills.  This  result  is  not  unimportant,  because  it  shows  that  the  region  is 
deeply  eroded  and  establishes  another  point  of  resemblance  between  the 
rocks  of  this  group  here  and  elsewhere. 

The  degree  of  metamorphism  of  the  Knoxville  beds  of  Clear  Lake 
varies  greatly.     Some  of  the  sandstones  are  extremely  little  altered  and 

O  •/  v 

are  characteristic  micaceous  arcose.  Granular  metamorphics,  glaucophane 
schists,  and  serpentine  also  occur ;  but  the  transitions  are  so  frequent  and 
seemingly  so  capricious  that  it  would  be  impossible  to  define  the  different 
varieties  by  areas. 


Fie.  5.  Rr.ptures  produced  li.v  i'iiinpn'*simi  <i['sti:it;i. 

structu  e  of  the  ranges The  regularity  of  some  of  the  ranges  is  in  strong 

contrast  to  the  irregular  disposition  of  the  strata  and  is  possibly  duo  to  the 
combined  effect  of  plication  and  metamorphism.  If  a  series  of  bods  is 
tin-own  into  folds,  as  in  the  accompanying  diagram  (Fig.  f>),  it  is  rloar 
that  the  upper  surface  of  the  anticlinals  will  tend  to  crack  open  and  also 
that  a  similar  tendency  will  exist  in  the  lower  surface  of  the  synclinals. 
If  metamorphism  is  then  induced  by  rising  waters  holding  mineral  matter 
in  solution,  such  as  silicic  acid,  the  compressed  under  surface  of  the  anti- 
clinal will  offer  a  resistance  to  percolation,  while  the  fractured  under  sur- 


CHICO-TEJON  SEEIES.  237 

face  of  the  synclinals  will  afford  paths  of  least  resistance.  Metamorphism 
thus  induced  will  therefore  affect  the  synclinals  more  than  the  anticlinals, 
and,  if  erosion  follows,  not  only  will  tlie  relief  and  the  fractured  surface  of 
the  anticlinals  tend  to  their  degradation,  but  the  resistance  of  the  synclinals 
will  be  increased  by  the  silicih'cation  and  cementation  of  the  mass.  It  is 
quite  conceivable  that  the  combined  effect  of  plication  and  metamorphism 
as  here  imagined  should  be  such  as  to  result  in  a  much  more  regular  mod- 
eling of  the  surface  by  erosion  than  would  have  been  induced  had  either 
plication  or  metainorphisin  alone  influenced  the  course  of  degradation.1 

The  chico-Tejon  series.  —  Toward  the  southern  end  of  the  map  the  Chico-Tejoii 
scries  appears.  It  consists  chiefly  of  soft  sandstones  of  a  tawny  hue  where 
exposed  to  oxidizing  influences,  but  bluish  in  color  below  the  water-line, 
as  is  usual  with  sediments  containing  a  small  amount  of  iron.  This  series, 
though  tilted  and  disturbed,  is  not  crushed  or  plicated  like  the  older  strata 
to  the  north.  It  also  includes  conglomerates  full  of  metamorphic  pebbles, 
in  some  cases  showing  an  unusually  brilliant  polish.  These  pebbles  are 
highly  siliceous  and  on  this  account  do  not  at  first  sight  appear  to  resemble 
the  extensively  developed  metamorphic  series.  In  cases  of  this  kind,  how- 
ever, it  is  necessary  to  remember  that  even  feldspathic  rocks  are  rapidly 
disintegrated  in  moving  water  and  that  quartz  is  almost  the  only  mineral 
which  will  long  retain  the  form  of  pebbles.  Concretions  are  common  in 
these  rocks,  occasionally  with  fossil  nuclei,  but  usually  without  any  dis- 
tinguishable nucleus.  They  sometimes  weather  more  and  sometimes  less 
rapidly  than  the  rock  in  which  they  are  embedded  and  are  often  composed 
of  concentric  shells.  Some  argillaceous  deposits  and  a  little  limestone 
occur  in  this  formation.  The  •  Chico-Tejon  series  of  this  region  is  fos- 
siliferous,  though  organic  remains  are  by  no  means  generally  distributed 
through  it.  Mr.  Gabb  collected  a  considerable  number  of  fossils  here,  and 
so  also  did  my  party. 

The  Chico-Tejon  series  does  not  come  in  contact  with  the  metamorphic 
rocks  in  such  a  way  as  to  demonstrate  a  non-conformity,  alluvium  arid  lava 
intervening  on  the  surface  ;  but  the  sudden  change  in  lithological  character 
and  the  comparatively  trifling  disturbance  of  the  unmetamorphosed  rocks 


1  See  Daua,  Manual  of  Geology,  p.  750. 


OF 

USIYERSIT7 


238  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

are  sufficient  to  suggest  a  non- conformity.  When  this  relation  lias  been 
shown  to  exist  elsewhere  it  is  manifest  that  it  affords  a  satisfactory  explana- 
tion of  the  facts  at  Clear  Lake. 

No  Miocene  strata  have  been  detected  with  certainty  in  this  part  of 
the  country.  It  is  possible  that  such  were  deposited  and  have  since  been 
completely  removed  by  erosion ;  but  this  appears  to  me  very  unlikely. 
Remnants  of  them  would  almost  inevitably  have  been  preserved,  if  not 
elsewhere,  at  least  beneath  the  fresh-water  Pliocene.  I  believe  it  much 
more  probable  that  a  gradual  rise  of  this  region  took  place  in  the  early 
Tertiary,  such  as  has  occurred  in  recent  times  throughout  the  State,  and 
that  during  the  Miocene  this  was  a  land  area.  No  violent  uplift  can  have 
intervened  between  the  Tejon  (Eocene)  and  the  Miocene,  however;  for, 
wherever  the  two  come  in  contact,  as  is  frequently  the  case  to  the  south, 
they  almost  always  appear  entirely  conformable. 

First  andesitic  eruption. — After  the  deposition  of  the  Cliico-T ejon  rocks  the 
first  geological  event  traced  was  the  eruption  of  Chalk  Mountain.  This 
was  probably  coeval  with  the  ejection  of  some  of  the  rock  near  Thurston 
Lake.  These  lavas  are  dense. pyroxene-andesites,  which  have  been  described 
in  Chapter  IV.  Chalk  Mountain  lies  upon  the  north  fork  of  Cache  Creek, 
about  half  a  mile  above  the  highest  point  of  the  creek  shown  on  the  map. 
It  is  a  small  conical  hill,  from  a  part  of  which  the  heavy  bases  have  been 
extracted  by  sulphur  springs,  still  feebly  flowing.  Portions  of  the  mass 
are  fresh,  however.  Chalk  Mountain  rests  upon  crumpled,  metamorphic 
strata,  which  were  deeply  eroded  before  the  ejection  of  the  rock.  The 
outflow  of  this  rock  certainly  preceded  the  Cache  Lake  period,  for  the  lake 
beds  are  found  upon  its  sides,  and  fragments,  either  from  Chalk  Mountain 
or  from  other  unknown  masses  of  precisely  similar  Hthological  character, 
are  abundant  throughout  all  the  lake  beds  shown  on  the  map.  Chalk 
Mountain  may  have  somewhat  antedated  Cache  Lake,  but  there  is  as  yet 
nothing  to  indicate  an  interval,  and  it  seems  more  probable  that  its  eruption 
accompanied  the  orographical  changes  which  in  the  Pliocene,  and  probably 
early  in  that  period,  dammed  back  the  waters  of  the  region. 

cache  Lake  beds. — That  Cache  Lake  occupied  an  extensive  area  is  certain. 
It  extends  to  the  east  an  unknown  distance,  and  how  great  a  proportion 


PLIOCENE  DEPOSITS.  239 

of  it  is  included  in  the  map  has  not  been  ascertained.  These  beds  consist, 
first,  of  conglomerates,  carrying  pebbles  of  metamorphic  rock  identical 
with  that  which  underlies  them,  and  of  pyroxene-andesite  which  cannot  be 
discriminated  from  that  of  Chalk  Mountain;  secondly,  of  s..ind  beds;  and, 
thirdly,  of  argillaceous  and  calcareous  deposits.  For  the  most  part  the  strata 
are  but  little  compacted  and  may  be  reduced  to  powder  in  the  hand;  but  there 
are  frequently  nodular  masses  which  are  consolidated  to  firm  rock.  Some  of 
the  bluffs  of  conglomerate — for  example,  those  in  Grizzly  Canon  —  are  stud- 
ded with  such  nodules,  distributed  somewhat  uniformly  over  the  surface. 
Elsewhere  single  strata  of  sand  or  clay  are  petrified,  and  occasionally,  as 
on  Perkins's  Creek,  considerable  areas  of  sandstone  fully  solidified  are  met 
with.  The  impression  conveyed  by  the  prevalent  distribution  of  the  more 
extended  and  irregular,  hardened  masses  is  that  they  represent,  the  local 
action  of  cold,  calcareous  or  siliceous  waters  upon  the  surrounding  rock,  an 
action  which,  if  sufficiently  prolonged,  would  result  in  the  complete  pet- 
rifaction of  the  whole  system  of  beds.  A  similar  effect  of  mineral  springs 
on  recent  deposits  may  be  seen  at  several  points  in  the  district,  particularly 
along  Sweet  Hollow  Creek.  The  isolated  nodules  cannot  be  produced  in 
this  way  and,  like  those  in  the  Chico  of  New  Idria,  they  are  probably  due  to 
the  decomposition  of  organic  matter,  as  explained  in  Chapter  III. 

The  Cache  Lake  beds  have  been  subjected  to  comparatively  little  dis- 
turbance. They  are  tilted  at  angles  varying  from  10°  to  about  40°,  but  the 
inclination  seldom  changes  rapidly,  and  there  is  very  rarely  anything  which 
can  be  regarded  as  contortion.  Within  the  area  of  the  map,  too,  no  faulting 
was  traced,  though  more  or  less  important  disturbances  of  this  nature 
occur  near  Chalk  Mountain  and  on  the  north  fork  of  Cache  Creek,  east  of 
the  map  limit.  The  thickness  indicated  by  measuring  the  strata  perpen- 
dicularly to  the  planes  of  stratification  is  very  great — some  thousands  of 
feet.  I  confess  myself  unable  either  to  comprehend  this  or  to  ignore  its 
significance.  There  i.s  certainly  no  confusion  between  these  beds  and 
others  of  marine  origin,  since  fresh-water  shells  were  found  in  them  at 
widely  separated  horizons;  but  the  accumulation  of  several  thousand  feet 
of  sediment  in  any  lake  except  one  of  vast  dimensions  seems  an  impossi- 
bility. A  careful  search  was  made  for  faults  without  finding  any.  The 


240  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

probabilities,  however,  seem  to  me  in  favor  of  tlie  supposition  that  these 
really  exist,  but  thus  far  have  escaped  detection.  Even  on  this  assumption 
I  believe  it  impossible  to  reduce  the  estimate  of  the  thickness  of  this  deposit 
below  1,000  feet. 

cache  Lak=  fossils. — The  argillaceous  strata  of  the  Cache  Lake  period  are 
full  of  organic  remains,  but  unfortunately  these  are  chiefly  vegetable. 
Shells  were  detected  in  only  four  localities:  on  the  Grizzly  Canon  road 
near  the  top  of  the  divide  between  Burns's  Valley  and  the  north  fork  of 
Cache  Creek;  at  an  exposure  on  the  hillside  about  a  quarter  of  a  mile  north 
of  this  point;  close  to  the  mouth  of  Indian  Creek;  and  in  an  exposure  on 
Cache  Creek  a  quarter  of  a  mile  below  its  intersection  with  the  road  from 
Lower  Lake  to  Sulphur  Bank.  Of  these  the  first  and  second  are  much  the 
richest.  They  show  a  series  of  mollusks,  the  most  important  of  which  are 
identical  with  those  now  abundant  in  Clear  Lake,  while  all  of  them  survive 
on  the  Pacific  slope,  and  not  improbably  in  Clear  Lake  itself.  They  have 
been  enumerated  and  discussed  in  Chapter  V.  According  to  Mr.  Stearns, 
who  is  unquestionable  authority  on  this  subject,  they  show  that  the  physi- 
cal conditions  prevailing  in  Cache  Lake  were  not  markedly  different  from 
those  of  the  present  Clear  Lake.  The  peculiarities  of  form  of  one  of  the 
shells,  the  ordinary  Anodon  of  Clear  Lake,  are  also  such  as  to  show  that  in 
spite  of  the  difference  of  position  and  notwithstanding  the  very  great  oro- 
graphical  modification  which  the  country  has  undergone,  there  has  been  an 
absolute  continuity  of  life  from  the  Cache  Lake  period  to  the  present  time. 
No  doubt  mollusks,  and  particularly  locomotory  species  like  this  AnotJon, 
are  able  to  survive  tolerably  vigorous  disturbances,  but  the  facts  show  that 
from  a  faunal  point  of  view  the  elevation  of  these  lake  beds  was  not  cata- 
strophic. In  spite  of  careful  search  vertebrate  remains  were  found  in  only 
two  localities.  These  points  are  a  small  side  ravine  leading  into  Grizzly 
Canon  from  the  north  and  a  vineyard  near  Lower  Lake. 

other  characteristics. — As  might  be  expected  from  the  character  of  the  Cache 
Lake  deposits,  they  are  extensively  eroded.  In  many  cases  the  resulting 
forms  are  strongly  suggestive  of  those  of  the  Bad  Lands  of  Wyoming, 
showing  fantastic  pinnacles,  pillars,  and  gorges.  This  is  especially  notice- 
able north  of  Chalk  Mountain  and  in  Cub  Gulch.  In  most  portions  of  the 


PLIOCENE  DEPOSITS.  241 

area  the  erosion  lias  been  largely  controlled  by  the  stratification,  and  the 
resulting  hills  show  straight  slopes  on  one  side  parallel  to  the  stratification 
and  abrupt  declivities  on  the  other  where  the  strata  have  been  broken 
through.  As  seen  from  the  Grizzly  Canon  road  about  two  miles  south  of 
the  north  fork  of  Cache  creek,  a  succession  of  such  hills  might  be  taken 
for  a  series  of  monoclinal  uplifts.  Near  the  stream  the  Cache  Lake  strata 
have  also  been  extensively  terraced.  But,  while  the  erosion  of  these  beds 
has  been  considerable,  when  their  prevalent  earthy  character  and  exposed 
position  are  taken  into  consideration  it  is  clear  that,  geologically  speaking, 
they  must  be  comparatively  recent,  since  otherwise  they  would  long  ago 
have  been  washed  entirely  away. 

On  and  near  the  north  fork  of  Cache  Creek  the  lake  beds  are  covered 
unconformably  by  a  deposit  of  gravel  usually  50  feet  or  less  in  thickness. 
This  is  somewhat  obscurely  stratified,  unconsolidated,  and  has  been  tilted, 
though  less  than  the  underlying  lake  beds.  It  presents  no  strata  in  which 
there  would  be  any  hope  of  finding  fossils  and  its  origin  is  not  certain.  It 
may  possibly  represent  the  very  last  stages  of  Cache  Lake,  or,  as  seems  to 
me  more  probable,  the  earliest  river  deposits  after  the  close  of  the  Cache 
Lake  epoch. 

The  lake  beds  can  best  be  studied  in  the  eastern  corner  of  the  area 
mapped,  for  in  the  volcanic  areas  near  Lower  Lake  the  strata  have  been 
considerably  altered.  Especially  is  this  the  case  near  the  andesite,  which 
lies  upon  the  Cache  Lake  beds  conformably  and  has  produced  a  decidedly 
metamorphic  influence  upon  them.  Tin's  consists  in  depositions  of  calca- 
reous matter,  silica,  and  ferric  hydrates,  apparently  through  the  action  of 
hot  springs  or  of  water  heated  by  contact  with  the  volcanic  rock,  rather 
than  by  the  direct  influence  of  the  heat  of  the  lava.  Similar  results  are 
noticeable  where  the  basalt  has  come  in  contact  with  the  lake  beds;  for  ex- 
ample, near  the  lime  kilns,  northeast  of  Burns  Valley.  The  metamorphosed 
lake  deposits  yield  a  red  soil  full  of  white  masses  of  calcareous  rock,  which 
is  said  to  be  extremely  fertile. 

Relation  of  cache  Lake  to  clear  Lake. — As  may  be  seen  from  the  map,  Cache  Lake 
overlapped  the  area  at  present  occupied  by  Clear  Lake,  while,  as  Ir.is  been 
pointed  out,  the  identity  of  the  shells  in  the  two  find  other  circumstances 
MON  xm 1G 


242  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

show  that  their  history  must  have  been  continuous.  The  later  andesite, 
represented  by  Mt  Konocti,  overlies  the  latest  Cache  Lake  strata  and  also 
underlies  the  Clear  Lake  sediments.  It  is  impossible  to  avoid  the  conclu- 
sion that  the  erupt  ion  of  this  rock  accompanied  the  obliteration  of  Cache 
Lake  and  the  orographical  changes  which  confined  the  waters  to  their  pres- 
ent bed.  The  vertebrate  remains  in  the  vineyard  near  Lower  Lake  thus 
fix  the  geological  date  at  which  the  Cache  Lake  period  terminated  and  also 
the  date  of  the  eruption  of  the  asperites  of  Mt.  Konocti.  As  was  noted  in 
Chapter  V,  the  vertebrate  fossils  are  Pliocene,  while  the  amount  of  erosion 
and  the  relations  to  the  modern  lake  beds  show  that  they  are  Upper  Plio- 
cene. The  date  of  the  eruptions  is  thus  fixed  at  about  the  close  of  the 
Pliocene  epoch. 

Later  andcsitic  eruption. — The  later  andesite  is  most  prominently  represented 
by  Konocti  (or  Uncle  Sam)  Mountain,  but  the  same  rock  covers  a  large 
area  to  the  southeast  and  a  considerable  tract  to  the  northeast  of  the  more 
southerly  branch  of  the  lake.  It  is  described  from  a  microscopical  point 
of  view  in  Chapter  IV.  The  prevalent  variety  of  the  rock  is  a  coarse- 
grained porphyry,  sometimes  dark  and  sometimes  rather  light  colored. 
One  of  its  marked  features  is  the  frequency  of  laminated  structure.1  The 
laminae  are  usually  half  an  inch  or  more  in  thickness  and  not  very  sharply 
divided  from  one  another.  Weathered  surfaces  of  such  rock  are  corrugated, 
and  at  a  little  distance  the  rock  might  be  thought  sedimentary  rather  than 
volcanic.  Where  heavy  masses  are  cut  through,  columnar  structure  is 
sometimes  seen.  It  rs  particularly  fine  near  Little  Borax  Lake.  Between 
Konocti  and  Thurston  Lake  there  are  also  vast  quantities  of  obsidian  and 
pumice,  the  former  covering  almost  continuously  a  large  tract,  through 
which  the  road  from  Kelseyville  to  Lower  Lake  passes.  On  this  line  it  is 
about  four  miles  in  width  and  it  is  said  to  extend  a  still  greater  distance 
to  the  southwest.  The  best  locality  for  the  study  of  these  forms  is  on 
Thurston  Creek,  between  one  and  two  miles  northwest  of  Thurston  Lake. 
Here  the  obsidian  and  pumice  are  inter.bedded  with  the  porphyritic  ande- 

1  In  Geol.  Survey  California,  Geology,  vol.  1,  p.  96,  Professor  Whituey  states  that,  as  seen  from  the 
opposite  side  of  the  lake,  Uncle  Sara  appears  to  be  made  up  of  a  closely  folded,  synclinal  mass,  prob- 
ably of  somewhat  inctaiiiorphic  Cretaceous  sandstones.  This  impression  he  certainly  received  from 
the  exposed  cd^f.s  of  these  flows.  In  Auriferous  Gravels,  p,  23,  this  mountain  is  correctly  mentioned 

Dfi  volcanic. 


ASPEKITB.  243 

site,  all  being  intermingled,  often  with  the  accompaniment  of  transitional 
forms.  In  some  cases  nodules  of  obsidian  are  immediately  inclosed  in  con- 
centric layers  of  pumice  and  vesicular  obsidian,  while  in  other  instances 
angular  fragments  of  obsidian  are  directly  embedded  in  structureless  pumice. 
In  this  locality  the  stream  has  cut  through  solid  obsidian,  leaving  sheer 
walls  ten  or  more  feet  in  height.  Elsewhere  in  the  district  this  glass  is 
rarely  found  exposed  in  place,  owing  to  its  tendency  to  break  up  into  small 
fragments  which  cover  the  surface.  The  andesitic  obsidian  is  usually  dis- 
tinguishable with  ease  from  basaltic  glass  by  its  higher  and  more  resinous 
luster  and  its  greater  opacity.  The  andesitic  origin  of  this  glass  is  demon- 
strated by  its  manner  of  occurrence.  The  microscopic  character  agrees  with 
this  reference. 

About  three  miles  from  Kelsey  ville,  on  the  Lower  Lake  road,  and  again 
a  little  northwest  of  Thurston  Lake,  stratified,  andesitic  tufa  is  found  The 
former  occurrence  is  very  considerable  and  of  course  indicates  the  presence 
of  water  during  the  eruption,  though  Cache  Lake  beds  have  not  been  rec- 
ognized in  the  neighborhood.  The  presence  of  ponds  or  lakes  near  volca- 
noes is  of  course  a  usual  phenomenon,  due  to  the  damming  back  of  streams 
by  ejecta  or  to  more  or  less  important  orographical  changes. 

Age  of  the  younger  andesite Excepting     tll6     bed    of   Clear     Lake,     the    whole 

region  has  been  undergoing  erosion  ever  since  the  andesitic  eruption,  and 
the  surfaces  of  the  flanks  and  peaks  of  Konocti  show  that  the  degradation 
has  been  considerable.  There  is  no  recognizable  trace  of  a  crater  on  the 
peak;  on  the  contrary,  the  bedded  flows  of  rock  near  the  summit  are 
shown  in  cross  section.  Sufficient  time  has  elapsed  since  the  eruption  to 
permit  considerable  decomposition  in  exposed  masses  of  rock.  The  sum- 
mit, however,  is  more  exposed  to  degradation  than  the  general  surface  of 
the  country,  which  has  been  little  lowered  in  recent  times,  the  underlying 
metamorphic  Cretaceous  and  Pliocene  rocks,  where  they  have  been  pro- 
tected by  the  andesite,  not  lying  perceptibly  above  the  ordinary  level.  The 
main  area  of  andesite  southwest  of  the  lake  probably  overlies  metamorphic 
hills,  for  ajtered  Cretaceous  strata  appear  under  the  volcanic  rock  at  the  ex- 
tremity of  Elgin  Point  ("  Snake  Rocks")  and  at  Bailey  Point.  'The  pres- 
ent topography  of  the  country  between  Konocti  and  Thurstou  Lake  is 


244  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

scarcely  intelligible  except  upon  the  supposition  that  its  principal  features 
are  due  in  great  measure  to  those  of  the  original  lava  surface ;  for  it 
presents  a  series  of  elongated  basins  either  without  apparent  outlets  or  with 
only  very  narrow,  sharply  cut  outlets,  and  these  depressions  either  contain 
permanent  lakes,  like  Thurston,  or  winter  pools,  like  some  others  in  the 
neighborhood,  or  present  flat  surfaces  of  fine  soil,  evidently  the  result  of  the 
silting  up  of  lakes.  These  areas  of  sedimentation,  flanked  as  they  are  by 
massive  ridges  of  lava,  cannot  be  due  to  erosive  agencies,  and  there  is 
nothing  whatever  to  indicate  that  they  are  due  to  orographical  changes 
postdating  the  andesite  eruptions. 

Thurston  Lake. — Thurston  Lake  is  a  peculiar  body  of  water,  surrounded  on 
three  sides  by  heavy  masses  of  andesite,  with  high  and  steep  slopes.  On 
the  fourth  side,  toward  the  northwest,  the  lake  bottom  rises  at  a  very  slight 
angle  and  merges  into  an  elongated  valley  of  considerable  length.  The 
addition  of  a  few  feet  of  water  would  double  the  length  of  the  lake  in  this 
direction,  while  adding  almost  imperceptibly  to  its  extent  elsewhere.  The 
water  marks  show  that  the  height  of  water  varies  about  eleven  or  twelve  feet. 
In  spite  of  its  lack  of  any  visible  outlet,  this  lake  is  fresh  and  abounds 
in  animal  life,  some  of  the  fish  being  apparently  of  the  same  species  as 
those  of  Clear  Lake.  Its  fluctuation  is  also  sensibly  the  same  as  that  of 
Clear  Lake,  and,  as  nearly  as  can  be  estimated  without  a  special  survey  (a 
task  which  the  dense  brush  would  render  very  expensive),  its  level  is  the 
same.  The  only  probable  explanation  of  these  facts  would  seem  to  be  that 
there  is  an  underground  passage  between  the  lakes  —  a  supposition  in  which 
there  is  no  inherent  improbability,  since  channels  such  as  that  supposed 
frequently  exist  in  volcanic  masses,  especially  within  a  moderate  distance 
of  their  original  surfaces. 

Little  Borax  Lake. — As  has  been  seen,  there  is  much  structural  evidence  to 
show  that  the  andesitic  rock  of  Konocti  Mountain  is  not  recent,  but  that  it 
is  geologically  of  late  origin.  The  surroundings  of  Little  Borax  Lake,  how- 
ever, seem  to  indicate  a  local  activity  long  postdating  the  andesitic  erup 
tion.  This  little  saline  body  of  water  lies  in  a  crater-like  depression  at  the 
foot  of  the  mountain,  a  portion  of  the  walls  being  very  abrupt  and  evidently 
representing  fractured  surfaces,  while  the  basin  itself  contains  very  little 


MINES  IN  ANDKSITE.  245 

detritus.  Were  it  a  crater  anything  like  so  old  as  the  mass  of  the  mountain, 
an  outlet  would  almost  certainly  have  been  cut  through  the  low  swell  of 
land  separating  it  from  Clear  Lake  on  the  east  and  much  material  must 
have  fallen  into  the  basin  from  the  perpendicular  cliffs  of  columnar  andesite 
to  the  south.  On  the  other  hand,  there  seems  to  have  been  no  outflow  of 
lava,  either  andesitic  or  basaltic,  from  this  basin.  There  is,  moreover,  evi- 
dence that  Elgin  Point  has  been  considerably  raised  in  very  recent  times, 
and  it  appears  probable  that  the  basin  of  Little  Borax  Lake  was  formed  by 
an  explosive  outburst,  which  was  nearly  or  quite  contemporaneous  with  the 
basalt  eruptions  to  the  southeast.  A  partial  renewal  of  volcanic  activity 
on  the  old  line  of  eruption  at  a  period  of  volcanic  disturbances  in  the  im- 
mediate neighborhood  is  certainly  nothing  to  be  wondered  at.  The  origin 
of  the  borax  in  this  lake  is  no  doubt  entirely  similar  to  that  of  the  borax  in 
the  other  and  more  important  lake  near  Sulphur  Bank,  which  will  be  dis- 
cussed in  the  next  chapter.  There  are  now  no  hot  springs  flowing  into  it, 
though  there  are  warm  springs  associated  with  the  andesite  at  several  other 
points. 

Quicksilver  deposits  in  andesite. — At  two  localities  on  the  southern  side  of  Mt. 
Konocti  cinnabar  has  been  found.  One  of  these  is  close  to  the  base  and 
was  known  as  the  Bowers  mine.  It  is  abandoned,  and  all  that  could  be 
made  out  from  the  accessible  workings  was  that  the  associated  andesite  is 
quartzose  and  is  bleached  by  solfataric  action.  The  Uncle  Sam  mine  is  high 
up  on  the  flank  of  the  mountain.  It,  too,  is  in  dacite,  much  decomposed,  as 
if  by  the  action  of  heated  waters  or  gases.  A  considerable  quantity  of 
ore  was  formerly  extracted  at  this  point  and  sold  to  the  Sulphur  Bank 
Company,  but  statistics  were  not  obtainable. 

It  is  possible  that  the  dacite  eruptions  were  later  than  the  mass  of  the 
mountain  and  that  the  solfataric  action  accompanying  the  outflows  of  this 
rock  induced  the  deposition  of  ore,  but  no  conclusion  on  this  subject  was 
reached.  It  is  certainly  remarkable  that  the  only  dacite  occurrences  known 
in  the  district  are  thus  associated  with  the  only  quicksilver  deposits  known 
among  the  andesites. 

Basaltic  eruptions. — The  eruptions  of  basalt  of  the  Clear  Lake  region  were 
greatly  inferior  in  volume  to  those  of  andesite,  oven  more  so  than  would 


246  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

appear  from  an  inspection  of  the  map,  for,  owing  to  the  greater  fluidity  of 
the  lava,  the  basalt  fields  are  of  less  depth  than  the  andesitic  masses. 
While,  too,  some  general  orographical  changes  appear  to  have  accompanied 
the  emission  of  basalt,  as  was  almost  inevitable,  these  were  far  smaller 
in  amount  than  those  which  closed  the  Pliocene  epoch. 

The  basalt  of  the  region  under  discussion  is  a  fairly  typical  rock,  pre- 
senting the  usual  structural  peculiarities  and  mineralogical  composition  on 
the  whole,  though  the  distribution  of  olivine  is  irregular.  In  some  occur- 
rences this  mineral  forms  a  large  percentage  of  the  whole  mass,  while  in 
others  considerable  search  with  the  lens,  or  even  with  the  microscope,  must 
be  made  to  detect  it.  Very  interesting  glassy  forms  of  basalt  occur  near 
Borax  Lake,  of  which  farther  mention  will  be  made  in  the  next  chapter. 
It  does  not  appear  that  all  the  basalt  was  emitted  at  the  same  time,  or  even 
approximately  so,  for  the  evidences  of  erosion  on  some  of  the  areas  are  very 
perceptible,  while  on  others  there  has  been  no  considerable  degradation. 
On  the  whole,  the  basalt  must  be  considered  as  decidedly  recent,  for 
only  on  that  supposition  can  its  state  of  preservation  be  accounted  for. 
Thus,  McPike  crater  is  a  rounded  mass,  unfurrowed  by  rivulets,  at  the  top 
of  which  is  an  extremely  regular,  basin-like  crater  about  nine  hundred  feet 

•/          o 

in  diameter  and  fifty  to  one  hundred  feet  deep,  presenting  a  surface  entirely 
covered  with  lapilli.  That  this  basin  contains  no  water  is  probably  due  to 
the  porosity  of  the  sides,  which  seem  to  be  composed  of  lapilli.  The  walls 
are  unbroken  and  vegetation  has  only  begun  to  find  root  between  the  peb- 
bles. The  only  sign  of  age  is  the  fact  that  the  surfaces  of  the  lapilli  are 
reddened  with  ferric  oxide.  On  the  hills  directly  north  of  McPike  crater 
the  surface  is  covered  with  lapilli,  which  almost  entirely  conceal  the  under- 
lying metamorphic  rocks.  These  pebbles  could  not  possibly  have  been 
transported  to  their  present  position  by  water,  which,  on  the  contrary,  must 
eventually  sweep  them  down  into  the  valley.  In  fact,  they  appear  to  have 
fallen  as  they  lie  during  an  eruption,  since  which  there  has  not  been  suffi- 
cient rainfall  to  remove  them.  The  north  and  south  craters  at  Sulphur 
Bank  are  similarly  fresh,  excepting  that  in  each  case  one  side  of  the  crater 
is  broken  down;  but  there  is  no  evidence  that  this  is  a  result  of  erosion, 
for  there  is  no  stream  bed  or  dry  wash  leading  into  them.  Close  to  the 


BASALT. 

Sulphur  Bank,  on  Indian  Island,  on  Red  Hill,  and  west  oFTIbwer  Lake 
contorted  masses  of  lava  remain  on  the  surface,  where  they  chilled  after 
oozing  from  vents  or  from  cracks  in  the  lava  streams.  It  is  also  indicative 
of  the  lateness  of  the  basalt  eruptions  that  fragments  of  the  rock  are 
usually  to  be  found  only  in  the  immediate  neighborhood  of  the  main  areas. 
There  does  not  seem  to  have  been  time  enough  since  the  eruptions  to  effect 
any  general  or  even  widespread  distribution  of  pebbles.  At  Sulphur  Bank 
it  is  also  said  that  the  Indians  have  traditions  of  eruptions.  While  this  fact 
might  have  little  significance  were  any  portion  of  California  now  the  seat 
of  volcanic  activity,  it  seems  not  without  weight  when  it  is  remembered 
that  the  nearest  volcano  now  active  is  very  far  away.  At  all  events,  it 
seems  to  me  by  no  means  impossible  that  the  latest  eruption  may  have 
occurred  within  a  thousand  years  or  even  less. 

The  relations  of  the  basalt  areas  to  the  general  structure  of  the  under- 
lying metamorphic  rocks  are  not  easily  studied,  for  lack  of  exposures.  I 
have  endeavored  to  make  out  the  fissure  system  which  no  doubt  connected 
the  various  vents  of  the  basaltic  eruptions,  but  have  failed  to  reach  any  sat- 
isfactory conclusion. 

There  are  but  two  places  in  the  district  where  basalt  tables  occur.  Of 
these  one  is  at  the  extreme  eastern  end  of  the  McPike  area,  where  the  lava 
appears  to  have  followed  the  bed  of  the  north  fork  of  Cache  Creek  and  to 
have  been  subsequently  undermined  by  the  stream.  The  rock  has  fallen 
off  in  columns,  leaving  perpendicular  walls.  The  other  bluffs  are  com- 
prised in  the  area  northeast  of  Red  Hill,  and,  like  all  similar  occurrences,  are 
a  result  of  undermining.  In  both  cases  I  can  but  suppose  that  the  lava 
represents  much  earlier  eruptions  than  those  which  left  the  unimpaired  cra- 
ters nearer  the  Sulphur  Bank,  though  they  are  both  Post-Pliocene,  resting 
unconformably  upon  the  uplifted  Cache  Lake  beds. 

ciear  Lake. — Both  the  topography  and  an  examination  of  the  soils  show 
that  Clear  Lake  formerly  occupied  a  considerably  greater  area  than  it  now 
does.  The  flat  land  about  Sulphur  Bank  once  formed  a  portion  of  the  lake 
bottom,  and  Avould  again  do  so  were  the  lake  to  rise  50  or  70  feet.  A 
much  smaller  rise  would  flood  the  valley  now  in  part  occupied  by  Borax 
Lake,  the  surface  of  which  is  but  a  few  inches  above  the  level  of  the  lake. 


248  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

This  valley  must  once  have  been  much  deeper  than  now  and  in  part  have 
silted  up. 

Burns  Valley,  an  area  near  the  town  of  Lower  Lake,  the  whole  of 
Big  Valley,  and  portions  of  the  country  about  Upper  Lake,  as  well  as 
many  small  flats  along  the  lake  shore, .are  clearly  also  covered  with  recent 
lake  deposits. 

The  causes  which  might  have  produced  this  shrinkage  of  the  surface 
of  the  lake  are  erosion  of  the  outlet  or  orographical  changes,  or  both.  Had 
the  lake  bed  only  been  tilted  to  the  southeast,  the  tendency  would  have 
been  to  expose  the  bottom  to  a  considerable  depth  at  the  west  end,  but  not 
near  Lower  Lake.  Orographical  changes  alone  are  consequently  insuffi- 
cient to  explain  the  exposure  of  the  meadows.  Cache  Creek,  just  beyond 
the  limits  of  the  map,  passes  through  a  narrow  gorge  of  Cretaceous  sand- 
stone, and  the  mere  erosion  of  this  barrier  would  produce  the  effect  under 
discussion,  but  there  is  some  evidence  to  show  that  orograplncal  causes 
have  influenced  the  grade  of  Cache  Creek  and  consequently  its  capacity 
for  eroding  its  bed.  On  the  north  fork  of  Cache  Creek  the  banks  are  ex- 
tensively terraced  and  four  or  five  flood  plains  are  distinctly  visible.  This 
appears  to  mean  a  tilting  of  the  country  to  the 'eastward,  though  probably 
to  the  extent  of  only  a  very  few  inches  to  the  mile.  Such  a  widespread 
secular  change  would  increase  the  velocity  of  Cache  Creek,  as  well  as  of 
its  northern  fork,  and  accelerate  the  erosion  of  the  sandstone  gorge  near 
its  source.  Were  the  circumstances  more  favorable,  such  a  change,  if  it 
really  took  place,  might  be  detected  on  the  banks  of  the  lake,  which  would 
also  be  terraced.  Two  causes  seem  to  have  stood  in  the  way  of  such  a 
modification  of  the  shore.  The  first  of  these  is  the  resistance  offered  by 
the  sandstone  of  the  gorge,  which  would  yield  but  slowly  to  an  increased 
velocity  of  a  current  carrying  little  sand  in  suspension.  It  is  well  known 
that  the  erosive  power  of  lake  water  is  slight  because  it  is  so  free  from 
sand,  and  the  erosion  of  the  gorge  would  probably  be  still  slower  than  it  is 
were  it  not  for  the  fact  that  Herndon  Creek  flows  into  Cache  Creek  between 
the  lake -and  the  gorge.  The  second  influence  tending  to  prevent  the  for- 
mation of  terraces  is  the  tule  belt.  A  strip  of  these  reeds,  from  a  few  feet 
to  a  few  yards  in  width,  grows  almost  everywhere  along  the  lake  shore, 


CHANCES  OF  SURFACE.  249 

separated  from  the  beach  by  a  few  feet  of  open  water.  Even  when  the 
lake  is  in  a  state  of  very  considerable  agitation  scarcely  a  ripple  reaches 
the  shore  thus  protected,  and  not  only  is  the  erosion  of  the  banks  in  great 
measure  prevented,  but  sedimentation  is  favored,  so  that  in  some  places  the 
shore  appears  to  be  growing  into  the  lake  by  the  accumulation  of  tule 
roots  and  sediment.  On  the  whole,  therefore,  the  lowering  of  the  lake 
level  in  comparatively  recent  times  is  not  improbably  the  result  of  the  ero- 
sion of  the  bed  of  Cache  Creek,  assisted  by  a  very  gradual  and  gentle  tilt- 
ing of  the  whole  region  toward  the  east  or  southeast. 

Certain  limited  orographical  changes  have  unquestionably  taken  place 
about  the  lake  in  very  recent  times.  At  the  end  of  Elgin  Point  is  a  steep 
bank,  consisting  of  uncompacted  strata  of  material  precisely  similar  to  that 
found  on  the  old  lake  bottom  areas  at  the  Sulphur  Bank,  in  Big  Valley, 
and  below  the  high-water  mark  of  the  lake.  It  consists  of  mud,  in  which 
pebbles  of  metamorphic  rock  and  of  later  andesite  are  abundant.  In  the 
lower  strata  of  this  bank,  which  is  about  one  hundred  and  fifty  feet  high, 
scoriaceous  forms  of  andesite  occur,  which  are  no  longer  to  be  met  with 
on  the  surface  in  the  neighborhood.  The  southern  side  is  a  curved  slope 
parallel  to  the  planes  of  stratification  and  essentially  unsculptured  by  wa- 
ter, and  the  bank  would  seem  to  represent  an  uplift  of  about  the  same 
date  as  the  finely  preserved  craters  near '  Sulphur  Bank.  If  the  hypothesis 
suggested  with  regard  to  the  formation  of  the  basin  occupied  by  Little 
Borax  Lake  be  correct,  this  uplift  was  probably  its  concomitant.  These 
recent  strata  rest  in  part  upon  metamorphic  rocks  and  in  part  upon  the 
andesite  which  constitutes  the  main  mass  of  Elgin  Point.  A  very  similar 
bank  of  the  same  date,  but  less  well  exposed  for  study,  occupies  the  south 
side  of  the  entrance  to  Upper  Lake. 

It  is  the  inevitable  fate  of  lakes  to  be  filled  with  sediments  to  a  dead 
level,  but,  as  the  evidence  seemed  to  be  that  the  sediments  of  Clear  Lake 
are  not  of  great  thickness,  it  appeared  to  me  desirable  to  examine  the  to- 
pography of  the  bottom.  Several  hundred  soundings  were  made  for  this 
purpose,  the  results  of  which  are  shown  in  the  subaqueous  contours  on 
the  map  of  the  lake.  From  these  it  appears  that  the  water  is  deepest  near 
the  narrows,  as  would  be  the  case  if  the  lake  occupied  valleys  of  erosion 


250  QUICKSILVER  DEPOSITS  OF  THE  PAOIFIO  SLOPE. 

between  ranges  which  had  attained  essentially  their  present  configuration 
prior  to  the  formation  of  this  sheet  of  water. 

The  map,  in  accordance  with  the  rules  of  the  U.  S.  Land  Office,  shows 
the  outline  of  the  lake  at  high  water.  The  subaqueous  contours  are  referred 
as  nearly  as  may  be  to  the  same  level,  or  10  feet  above  the  lowest  point 
which  the  lake  has  reached  in  ten  years.  This  point  was  noted  by  Capt. 
R.  S.  Floyd,  who  has  kept  a  full  record  of  the  level  of  the  lake  referred  to 
throughout  this  period.  The  lake  occasionally  rises  a  little,  more  than  10 
feet  above  low-water  mark,  but  not  enough  to  make  any  important  differ- 
ence. 


CHAPTER  VII. 

DESCRIPTIVE  GEOLOGY  OF  SULPHUR  BANK. 

[Atlas  Sheet  IV.] 

sedentary  rocks  of  ths  district. — The  results  of  a  general  study  of  the  region 
of  Clear  Lake,  undertaken  for  the  purpose  of  throwing  light  upon  the  his- 
tory and  geological  relations  of  Sulphur  Bank,  have  been  presented  in  the 
preceding  chapter.  The  area  delineated  in  the  detailed  map  of  Sulphur 
Bank  includes  few  formations.  The  underlying  rock  everywhere  belongs 
to  the  Knoxville  series  (Neocomian),  representing  the  opening  of  the  Cre- 
taceous period.  This  rock  was  intensely  crushed  and  irregularly  metamor- 
phosed not  long  after  its  deposition,  but  neither  the  quicksilver  deposits  of 
this  locality  nor  those  of  any  other  included  in  this  memoir  were  formed 
at  the  epoch  of  metamorphistn.  All  the  varieties  of  metamorphic  rocks 
described  in  Chapter  III  occur  in  this  small  area,  from  almost  unaltered 
sandstones  up  to  material  so  highly  recrystallized  as  closely  to  resemble 
an  eruptive  porphyry.  Serpentine  is  also  found  in  very  small  quantities  on 
the  ridge  north  of  Borax  Lake.  It  appears  again  near  the  end  of  Sunken 
Point,  shown  on  Atlas  Sheet  III.  The  little  spot  of  serpentine  near  Borax 
Lake  might  be  shown  on  the- detailed  map  by  a  separate  color,  but  the  met- 
amorphism  is  so  irregular  in  intensity  that  it  would  be  quite  impossible  to 
delineate  areas  of  pseudodiabase,  pseudodiorite,  and  glaucophane  schist. 

No  eruptive  rocks  are  interbedded  in  the  metamorphic  series  at  Sulphur 
Bank.  This  was  established  by  careful  observation  in  the  field  prior  to  the 
microscopical  examinations.  The  latter  showed  that  some  specimens,  so  far 
as  their  microscopic  character  is  concerned,  might  possibly  be  either  ex- 

S51 


252  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

treme  members  of  the  crystalline  metamorphic  series  or  true  eruptive  rocks. 
The  region  was  revisited  for  the  purpose  of  verifying  the  structural  relations 
of  these  occurrences.  The  questionable  rocks  were  then  found  to  be  sur- 
rounded by  and  to  pass  over  into  indubitable  metamorphic  material  in  such 
a  way  as  to  preclude  any  separation  of  them. 

The  Sulphur  Bank  map  shows  no  Chico-Tejon  beds  or  Pliocene  fresh- 
water strata  and  no  andesite.  Here,  as  elsewhere  on  Clear  Lake,  it  is 
manifest  that  the  level  of  the  present  sheet  of  water  has  sunk  within  no 
very  long  period,  leaving  fertile  meadows.  The  composition,  as  well  as 
the  topographical  relations  of  these  meadows,  shows  that  they  are  drained 
portions  of  the  lake  bed,  for  they  are  full  of  roots  of  the  tule,  which  grows 
only  near  the  water's  edge  and  preferably  in  shallow  water.  Close  to  the 
basalt  and  in  beds  continuous  with  those  which  underlie  the  lava  these 
roots  are  sometimes  found  petrified. 

Basalt. — The  only  volcanic  rocks  on  this  map  are  basaltic,  but  their 
character  and  mode  of  occurrence  are  rather  unusual  and  therefore  interest- 
ing. They  are  in  part  olivinitic  and  in  part  free  from  olivine,  but  their 
microstructure  is  the  same  in  both  cases.  In  the  area  south  of  Borax  Lake, 
just  beyond  the  limits  of  the  map,  ordinary  olivinitic  basalt  occurs.  It 
adjoins  a  large  field  chiefly  composed  of  obsidian  and  pumice,  but  contain- 
ing also  rocks  which,  while  manifestly  in  part  glassy,  have  a  thoroughly  ba- 
saltic appearance.  It  is  impossible  to  separate  these  occurrences  in  the  field, 
and  the  more  they  are  studied  the  more  certain  it  appears  that  all  this  ma- 
terial is  substantially  from  a  single  eruption.  This  is  confirmed  by  micro- 
scopic examination,  although  the  glass  is  an  acid  one,  containing  over  75  per 
cent,  of  silica  (see  pp.  158-162).  The  glass  is  usually  of  a  gray  color  and 
is  transparent  even  in  masses  a  quarter  of  an  inch  or  more  in  thickness. 
Between  it  and  the  pumice  there  is  every  conceivable  gradation.  The 
glassy  forms  sometimes  include  small  fragments  of  crystalline  basalt.  This 
area  is  the  only  one  in  which  this  obsidian  appears  to  be  in  place,  yet  the 
dissemination  of  chips  of  the  same  glass  a  square  inch  or  less  in  area  is 
something  astonishing.  In  the  immediate  neighborhood  of  the  obsidian 
field  these  chips  are  so  plentiful  that  it  is  difficult  to  draw  its  outline  with 
any  accuracy.  They  gradually  grow  less  abundant,  but  are  still  to  be 


BASALTIC  GLASS.  253 

found  beyond  the  crests  of  the  hills  surrounding  the  locality.  Similar  chips 
are  occasionally  met  with  all  over  the  district;  but  this  is  in  part  due  to 
human  agency,  for  a  spearhead  of  this  glass  was  found  miles  away.  Most 
such  chips,  however,  are  quite  isolated  and  show  no  marks  of  artifice.  Ex- 
plosions attending  the  eruption  may  account  for  the  greater  part  of  the  frag- 
ments near  the  obsidian  field ;  how  the  more  distant  ones  were  transported 
I  cannot  guess 

Another  feature  of  the  basalt  of  this  district,  somewhat  unusual  in 
California,  but  not  unknown  in  other  portions  of  the  State,  is  the  formation 
of  regular  crater-cones.  Dense  basalts,  when  in  a  state  of  fusion,  are  prob- 
ably too  fluid  to  build  cones.  Those  at  Sulphur  Bank  are  composed  of 
extremely  porous  basalt,  much  of  it  in  the  condition  of  lapilli.  Each  of 
them  is  broken  through  on  one  side,  apparently  by  lava  streams,  not  by 
water.  The  lapilli  are  more  or  less  oxidized,  but  have  accumulated  no 
considerable  quantity  of  soil  and  are  not  concealed  by  the  scant  herbaceous 
vegetation,  though  trees,  particularly  conifers,  have  taken  root  among 
them.  Contorted  forms  of  lava,  too,  are  abundant  at  some  of  the  croppings 
and  everything  points  to  a  very  recent  date  of  eruption. 

General  description  of  the  bank — The  Sulphur  Bank  is  an  area  exhibiting  most 
manifest  indications  of  solfataric  action.  It  is  not  practicable  to  outline  the 
exact  area  of  decomposition,  which,  however,  is  substantially  coincident 
with  the  southein  half  of  the  small  basalt  area  in  which  it  lies,  including 

'  o 

all  the  more  elevated  portions  of  this  area.  The  ore-bearing  ground  takes 
in  a  narrow  strip  of  the  sedimentary  area  to  the  south.  The  surface  indica- 
tions of  solfatarism  consist  in  complete  decomposition  of  a  large  portion  of 
the  basalt  to  a  white,  pulverulent  mass,  sulphur  deposits,  and  hot  mineral 
springs  holding  gases  in  solution.  The  locality  was  first  worked  for  sulphur. 
At  a  distance  of  a  few  yards  below  the  surface,  however,  cinnabar  was 
found  occurring  with  the  sulphur,  and  lower  still  cinnabar  was  found  in 
large  quantities.  The  property  has  been  worked  for  the  most  part  by  open 
cuts,  with  little  regard  to  system.  Jts  appearance  is  very  peculiar.  The 
glare  of  white  decomposition-products,  the  labyrinth  of  deep,  open  pits  and 
trenches,  and  the  acrid  dust  and  evil  smells  of  the  locality  produce  a  strong 
impression  on  the  observer;  but  even  to  the  geologist  it  is  an  interesting 


254  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

rather  than  an  agreeable  one.  Work  in  these  cuts  is  so  trying  that  few 
white  miners  have  ever  accepted  employment  in  them  a  second  day  and 
almost  all  the  labor  is  performed  by  Chinamen. 

origin  of  the  basalt — To  my  mind  there  is  little  question  that  the  basalt  of 
the  Sulphur  Bank  was  erupted  on  the  spot.  In  the  comparatively  little 
decomposed  portions  of  the  area  contorted  forms  and  cindery  masses  of  the 
lava  still  exist.  This  shows  that  it  has  experienced  but  little  erosion.  The 
two  craters  shown  on  the  map  are  also  extremely  recent,  as  has  been 
pointed  out  in  the  preceding  chapter.  Between  the  craters  is  a  lava  stream 
of  very  evident  character ;  but  the  lava  is  not  continuous  from  the  craters 
to  the  bank,  the  highest  portion  of  which  is  over  50  feet  above  the  level 
of  the  ground  at  the  points  of  discontinuity.  Had  the  basalt  of  the  Sul- 
phur Bank  come  from  the  volcanoes,  its  original  surface  must  have  been 
lower  than  that  of  any  point  in  the  lava  stream  connecting  the  localities, 
and,  if  they  were  once  thus  connected,  at  least  50  feet  of  the  rock  has  since 
been  eroded.  There  is  no  ravine  crossing  the  track  of  the  flow  to  produce 
a  local  effect  of  this  kind,  and  the  surface  indications  entirely  preclude  the 
supposition  that  there  has  been  any  general  degradation  approaching  such 
an  amount  since  the  basalt  was  extruded,  or,  indeed,  any  sensible  amount 
of  degradation. 

I  look  upon  the  hot  springs  as  of  volcanic  origin  and  as  a  later  phe- 
nomenon than  the  ejection  of  the  basalt.  There  appears  to  be  nothing  to 
warrant  the  hypothesis  that  these  springs  were  in  action  before  the  basalt 
eruption.  On  the  contrary,  the  basalt  lies  upon  recent  lake  deposits,  some- 
times filled  with  tule  roots,  and  a  part  of  these  are  within  the  influence  of 
the  solfataric  action,  as  is  shown  by  their  petrifaction.  Had  these  springs 
existed  for  an  indefinite  time  before  the  basalt  was  ejected  the  tule  roots 
could  not  have  grown.1 

Deposition  of  sulphur. — The  composition  of  the  waters  from  different  portions 
of  the  Sulphur  Bank  varies  considerably,  but  that  a  large  portion  of  them 
carry  hydrosulphuric  acid  is  evident  from  the  smell.  The  formation  of 
sulphur  and  sulphuric  acid  from  hydrosulphuric  acid  by  oxidation  is  one  of 

'These  silicilieil  roots  of  the  tule  (Scirpus  Jaemtris)  bear  a  strong  resemblance  to  f'aitJiniles,  and 
my  specimens,  in  the  absence  of  sufficiently  full  information,  have  been  described  and  figured  by  Mr. 
Leo  Lesquereux  as  a  uew  species  of  that  geous  (Proc.  U.  S.  Nat  Mil.-).,  1887,  ji.  :i(i). 


SULP11UK  AT  SULPHUR  BANK.  255 

the  most  familiar  facts  of  chemical  geology  and  of  experimental  chemistry. 
The  relations  of  the  two  processes  are  readily  seen  from  a  therrao-chemical 
standpoint,  for  the  reaction 

H2S  +  40  =  H-S04  liberates  "207,500  calories  and 
H2S+   0-IFO  +  S  liberates  59,100  calories. 

Hence  if  oxygen  is  present  in  excess,  as  it  is  at  the  surface  of  sulphur 
springs  and  in  porous  sinters  partially  saturated  with  solutions  of  hydro- 
sulphuric  acid,  this  will  simply  be  oxidized  to  sulphuric  acid.  But  if  oxy- 
gen is  deficient,  as  it  must  be  a  short  distance  from  the  surface,  a  single 
atom  of  oxygen  by  combining  with  JfPS  to  4H2SO'  would  produce  only 
50,375  calories,  or  8,725  less  than  it  sets  free  according  to  the  second  of 
the  above  reactions.  Assuming,  therefore,  that  the  two  reactions  are  ac- 
complished in  nearly  the  same  time,  sulphuric  acid  will  be  formed  at  the 
surface  of  such  a  region  as  the  Sulphur  Bank  and  free  sulphur  below  the 
surface.  This  is  in  correspondence  with  observations  at  sulphur  springs  the 
world  over  and  with  laboratory  experiments.  When  sulphides  of  the  alka- 
lis are  present  the  reactions  are  more  complex,  but  sulphur  is  also  separated 
while  hyposulphites  are  formed.  There  is  thus  nothing  strange  or  novel  in 
the  occurrence  of  sulphur  under  the  conditions  present  at  Sulphur  Bank. 

A  portion  of  the  sulphur  occurring  at  the  Sulphur  Bank  is  formed  by  a 
slightly  different  reaction.  Both  on  the  surface  and  in  the  mine  sulphurous 
acid  may  be  smelt,  and  early  in  1887  the  odor  of  this  gas  was  suffocatingly 
strong,  even  at  some  distance  from  the  Hermann  shaft.  The  sulphurous 
acid  undoubtedly  comes  up  with  the  other  volcanic  emanations,  though  per- 
haps not  in  direct  contact  with  the  hydrogen  sulphide.  Hydrogen  sulphide 
and  sulphur  dioxide  decompose  mutually,  forming  water  and  sulphur.  As 
a  consequence,  the  timbers  of  the  building  above  the  shaft  were  coated  with 
incrustations  of  sulphur  crystals  in  February,  1887,  and,  at  the  Fiedler 
shaft  as  well,  sulphur  crystals  had  deposited  in  smaller  quantity  by  the  same 
method. 

sulphuric  acid  and  its  effects. — The  sulphuric  acid  formed  at  or  close  to  the  sur- 
face percolates  downward  to  some  extent  and  is  eventually  neutralized  by 
free  bases  and  by  salts  of  feebler  acids.  The  neutralization  of  the  acid  is 
chief! v  effected  bv  the  sodium  carbonate  broughtjw^EttejrJfcat  waters  and 


256  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

aided  by  the  ammonia.  The  basalt  is  attacked  by  the  acid  waters  and  no 
doubt  by  the  sulphuric  acid  they  contain.  It  is  true  that  labradorite  and 
augite  are  but  little  acted  upon  by  acids  in  laboratory  experiments,  but  this 
basalt  has  been  exposed  to  the  action  of  hot  sulphuric  acid  for  hundreds  of 
years  at  least.  Its  resistance  is  also  considerable,  many  kernels  of  fresh 
rock  remaining  in  the  decomposed  envelopes. 

concentric  decomposition. — It  is  clear  from  numerous  exposures  that,  after  the 
basalt  solidified  at  the  Sulphur  Bank,  it  was  divided  by  cracks,  marking  in 
many  cases  a  distinct  though  imperfect  columnar  structure.  As  usual,  also, 
there  were  cross-fissures  in  the  vertical  columns.  These  cracks  formed  the 
passages  by  which  the  waters  reached  the  surface  and  by  which  the  acid 
formed  at  the  surface  became  diffused.  The  solid  masses  of  basalt  sepa- 
rated by  cracks  from  surrounding  blocks  were  attacked  from  the  outside 
by  the  acid  waters.  As  decomposition  progressed  successive  shells  were 
formed,  which  grow  more  and  more  spherical  as  the  centers  are  approached. 
This  has  been  attributed  to  "ball  structure"  in  the  rock,  but  it  appears  to 
me  unnecessary  to  assume  any  such  predisposing  cause,  of  which  there  is 
no  other  evidence  in  the  structure  of  this  lava  either  macroscopically  or 
microscopically.  It  is  shown  in  an  earlier  portion  of  this  work  (page  G8) 
that  this  conformation  is  the  natural  result  of  the  action  of  a  corrosive  fluid 
on  a  slightly  porous,  tolerably  homogeneous  material  in  .blocks  which 
approximate  to  regular  polyhedrons  in  form.  The  concentric  shells  which 
are  so  well  developed  here  are  themselves  the  results  of  the  decomposition 
process  and  are  not,  in  my  opinion,  pre-existing  envelopes  the  presence  of 
which  has  controlled  the  course  of  decomposition.  Decomposed  basalts 
showing  this  structure  so  strikingly  do  not  occur,  to  my  knowledge,  else- 
where in  California,  though  such  are  found  in  other  parts  of  the  world. 
An  instance  from  Great  Britain  similar  to  that  of  Sulphur  Bank  is  illus- 
trated by  Dr.  Geikie.1 

The  ultimate  residue,  when  the  attack  is  complete,  is  almost  pure  silica. 
The  depth  to  which  the  basalt  has  been  decomposed  by  the  acid  waters 
varies  in  different  exposures,  and  perhaps  averages  20  feet.  The  limit  is 
usually  very  sharply  defined,  and  it  may  be  considered  certain  that  this 

1  Text  Book  of  Geology,  1st  eil.,  Fig.  8(i. 


OCCURRENCE  OF  CINNABAR.  257 

represents  the  permanent  level  of  the  alkaline  waters  prior  to  the  beginning 
of  mining  operations. 

occurrence  of  cinnabar — The  mode  of  occurrence  of  cinnabar  at  the  Sulphur 
Bank  is  interesting  and  significant.  It  does  not  occur  in  sensible  quanti- 
ties at  or  close  to  the  surface,  but  is  found  to  a  considerable  extent  mixed 
with  sulphur  in  the  lower  portion  of  the  zone  of  oxidation.  The  principal 
deposits  are  below  this  level.  They  are  found  in  the  more  or  less  decom- 
posed basalt,  in  the  underlying  recent  lake  bottom,  and  in  the  Knoxville 
shales  and  sandstones.  The  cinnabar  is  associated  chiefly  with  silica,  in 

*>  , 

part  crystalline  and  in  part  amorphous.  In  the  lava  it  appears  as  small 
seams,  which  commonly  follow  either  the  original  cracks  between  the  blocks 
or  the  concentric  surfaces  of  the  decomposed  masses.  In  the  lake  deposits 
below  the  basalt  the  cinnabar  is  found  as  impregnations  or  irregular  seams. 
In  the  workings  from  the  Hermann  shaft  the  ore  occurs  exactly  as  it  does 
in  most  of  the  quicksilver  mines  of  California,  more  or  less  completely  fill- 
ing interstices  in  shattered  rock  masses.  Sometimes  ore  of  this  kind  has 
been  found  which  was  simply  a  brecciated  mass  of  rock  cemented  by  cin- 
nab*ar.  The  cinnabar  in  these  cases  has  crystallized  on  the  rock  fragments, 
exactly  as  quartz  often  does,  and  frequently  leaves  hollow  inclosed  spaces.1 
To  a  small  extent  the  more  porous  sandstones  have  been  impregnated  with 
ore.  Besides  quartz,  iron  pyrites  and  marcasite  frequently  appear  in  the 
gangue,  calcite  is  not  uncommonly  also  present,  and  small  quantities  of 
bitumen  are  often  found.  It  is  a  fact  of  great  interest  that  Dr.  Melville 
has  found  small  quantities  of  both  gold  and  copper  in  the  marcasite  accom- 
panying the  cinnabar.  The  inferences  to  be  drawn  from  the  mode  of  oc- 
currence of  the  cinnabar  at  this  locality  are  not  unimportant.  The  intimate 
association  of  the  ore  with  sulphur,  opal,  quartz,  pyrite,  and  to  a  smaller 
extent  with  calcite,  is  amply  sufficient  to  show  that  it  has  been  deposited 
from  water.  This  would  also  be  clear  if  the  cinnabar  were  not  accom- 
panied by  and  mixed  with  minerals  which  can  have  formed  only  in  the 
wet  way.  The  vuggs  lined  with  cinnabar  and  the  relations  of  the  veinlets 
of  ore  to  the  fissure  system  of  the  rocks  are  of  a  character  to  convince  any 

1  See  an  illustration  of  such  a  specimeu  iu  Le  Conte  ami  Rising's  paper  on  this  locality  (Am.  Jour. 
Sci.,  3:1  scries,  vol.  24,  1882,  p.  '«.)). 

MON   XIII 17 


258  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

practiced  observer  that  the  deposition  has  taken  place  from  solution,  and 
not  from  vapor.  The  occurrence  also  limits  the  possibilities  as  to  the 
origin  of  the  ore.  The  formation  of  sulphur  is  still  going  on,  and  so  also 
must  be  the  decomposition  of  the  basalt  and  the  deposition  of  pasty  hy- 
drous silica.  The  association  of  cinnabar  with  the  sulphur  and  its  deposi- 
tion along  the  concentric  partings  of  the  decomposed  basalt  blocks  close  to 
the  fresh  nuclei  show  that  cinnabar  is  either  now  being  deposited  or  that 
its  deposition  has  ceased  only  very  recently  and  must  have  gone  on  while 
the  conditions  were  almost  precisely  those  now  existing. 

The  copiously  flowing  springs  which  existed  here  before  mining  opera- 
tions began  and  the  sulphur  deposition  show  that  the  waters  rising  toward 
the  surface  come  from  a  considerable  depth.  This  must  have  been  the 
case  during  the  entire  period  of  sulphur  deposition.  The  ore  cannot  have 
leached  downward  from  the  basalt  into  the  underlying  rocks,  nor  can  a 
trace  of  quicksilver  be  detected  in  the  undecomposed  basalt.  Neither  can 
the  quicksilver  have  been  derived  from  the  layer  of  recent  lake  deposits  un- 
derlying the  basalt.  This  layer  is  thin,  at  least  in  places,  and  lies  hundreds 
of  feet  above  some  occurrences  of  the  ore.  The  original  source  of  the  quick- 
silver must  then  have  been  either  in  the  Knoxville  beds,  chiefly  sandstone, 
or  below  them.  This  sandstone  is  proved  by  microscopic  examination  to 
be  arcose,  or  granitic  detritus,  and  abundant  evidence  has  been  given  in 
preceding  chapters  to  show  that  granite  underlies  the  Coast  Ranges.  The 
source  of  the  quicksilver  is  consequently  either  granitic  detritus  or  granite 
or  it  lies  below  the  granite.  Further  than  this  the  facts  at  this  one  locality 
do  not  justify  conclusions  as  to  the  origin  of  the  ore. 

soifatanc  springs. — A  very  remarkable  feature  of  this  mine  is  the  abundance 
of  hot  springs,  frequently  carrying  gases.  These  gases  are  often  ammoni- 
acal  and  many  of  them  carry  sulphureted  hydrogen.  Others  again  have 
a  nauseous  smell  which  plainly  indicates  an  organic  origin.  An  analysis  of 
gas  from  the  Hermann  shaft  gave  — 

Carbon  dioxide,  CO2 89.34 

Hydrogen  sulphide,  H2S 0.23 

Marsh  gas,  CH< 7.94 

Nitrogen,  N 2.49 

Total..  100.00 


HOI  WATER  AT  SULPHUR  BANK. 


259 


On  the  southwest  drift  of  the  fifth  level  hot  water  and  vapor  are  expelled 
from  cracks  with  some  force  and  with  a  noise  resembling  that  of  escaping 
steam.  The  quantity  of  steam  condensed  to  a  visible  vapor,  however,  is 
not  very  great,  and  the  thermometer  stows  only  80°  C.  (176°  F.).  The 
escaping  gases  smell  of  ammonia.  This  is  the  hottest  water  met  with, 
though  other  springs  show  over  70°  C.1 

composition  of  the  waurs. — It  being  clear  that  the  cinnabar  has  come  to  the 
surface  in  solution  under  conditions  little  if  at  all  different  from  those  now 
prevailing,  the  composition  of  the  waters  becomes  a  matter  of  special  in- 
terest. The  following  analyses  show  the  composition  of  the  contents  of 
1,000  cubic  centimeters  of  hot  water  from  two  of  the  shafts  in  their  prob- 
able combinations: 


Hermann 
shaft. 

Parrott 

shaft. 

Silica  SiO*                         ... 

0  03715 

Ferrous  carbonate,  FoCO3  

0  00008 

Calcium  sulphate,  CaSO4  

0  0^340 

Calcium  carbonate,  CaCO3  

0  035°0 

0  05055 

0  01890 

Sodic  carbonate  Na2COs  

1  94675 

Ammonium  carbonate  (H4N)2C03  

0  00664 

0  00k>8° 

Borax,  Xa»B*O7  

1  87840 

Sodic  sulphate,  Na2SO*  

Sodium  chloride,  NaCl  

1  10^70 

Potassium  chloride,  KCI      k 

Fixed  organic  matter  

0  00500 

0  00760 

Hydrogen  sulphide  H2S  

Carbon  dioxide,  CO2  ,  

0  26^41 

Total  weight,  grams  .'  

5  3G815 

The  simple  instead  of  the  acid  carbonate  of  sodium  is  assumed  in  these 
analyses  because  the  acid  salt  is  at  least  in  part  dissociated  in  hot  solutions. 
The  sulphydric  acid  was  combined  to  some  extent  as  a  soluble  sulphide,  but 
with  what  base  it  was  united  was  not  ascertained.  Not  a  trace  of  mercury 
could  be  detected  in  solution,  though,  as  will  be. seen  in  Chapters  XI  and  XV, 
waters  very  similar  to  these  are  certainly  capable  of  dissolving  cinnabar. 

Nature  of  the  mercurifcrous  solutions. 111   the   hope   of    obtaining     fui'tllCr     light     OU 

this  subject  Dr.  Melville  visited  Sulphur  Bank  with  chemical  appliances 

1 1  am  not  aware  that  mining  operations  have  ever  been  carried  on  before  where  the  inflowing 
water  had  so  high  a  temperature  as  176°  F.  The  highest  temperature  which  I  observed  in  the  Corn- 
stock  was  170°  F. 


260  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

early  in  1887.  The  most  favorable  opportunity  for  investigating  the  water 
at  that  time  was  presented  at  the  Fiedler  shaft,  which  communicates  below 
ground  with  the  Hermann  shaft.  Both  had  then  been  abandoned  and  water 
escaped  from  the  top  of  the  former  into  the  lake.  Its  temperature  was 
128°  F.  (53J°  C.)  and  it  was  in  a  constant  state  of  agitation  from  the  es- 
cape of  carbon  dioxide  and  hydrogen  sulphide.  Large  quantities  of  water 
were  collected  in  new  wooden  pails  and  filtered  hot.  The  filtrate  on  evap- 
oration and  analysis  showed  all  the  substances  recorded  in  the  above  anal- 
yses, and,  in  addition,  alumina,  manganese,  cobalt,  phosphoric  acid,  hypo- 
sulphurous  acid,  and  some  organic  matter  resembling  humic  or  crenic  acid. 
Repeated  experiments  showed  not  a  trace  of  mercury,  though  the  filtered 
water  left  small  quantities  of  mercuric  sulphide  on  the  filter. 

This  water  under  these  physical  conditions  would  thus  appear  to  be 
incapable  of  dissolving  cinnabar ;  for  otherwise  the  suspended  sulphide 
must  have  been  accompanied  by  the  same  substance  in  solution.  This  in- 
solubility is  probably  ascribable  to  the  ammonia  present;  for  in  laboratory 
experiments  we  have  found  that  different  ammonia  compounds  precipitate 
mercuric  sulphide  from  analogous  solutions.  It  is  not  impossible  that  at 
pressures  above  one  atmosphere  ammonia  compounds  lack  this  precipitating 
power,  and  if  the  waters  of  Sulphur  Bank  were  always  amvuoniacal,  as  they 
have  certainly  been  for  the  last  twenty  years,  this  hypothesis  would  account 
for  the  fact  that  no  cinnabar  whatever  appeared  at  the  surface  of  the  Sul- 
phur Bank,  the  ore  being  met  with  only  at  a  depth  of  several  yards.  It 
would  also  account  for  the  mercuric  sulphide  in  suspension  in  the  water. 

The  ores  of  the  open  cuts  of  the  bank  were  also  submitted  to  a  care- 
ful examination,  in  order  to  ascertain  the  correspondence  between  their 
composition  and  that  of  the  material  dissolved  in  the  waters.  In  immediate 
contact  with  the  cinnabar  all  of  the  bases  detected  in  the  water  were  found, 
but  neither  chlorine  nor  boracic  acid.  A  sufficient  reason  for  the  absence 
of  these  acids  appears  to  be  the  solubility  of  the  chlorides  and  the  borates, 
which  have  never  been  found  in  any  of  the  quicksilver  mines  beneath  the 
surface,  though  at  Knoxville  and  at  Steamboat  Springs  borax  exists  in  the 
waters,  and  it  was  very  probably  also  present  during  the  time  of  ore  depo- 
sition at  other  mercuriferous  localities.  That  the  ores  of  Sulphur  Bank 
have  been  in  contact  with  solutions  of  chlorides  and  borates  is  very  cer- 


DEPOSITS  FROM  HOT  WATER.  261 

tain,  for  the  water  of  the  mine  carries  a  large  amount  of  them,  and,  in  the 
underground  workings  near  ore,  I  collected  efflorescences  largely  consisting 
of  them,  as  was  proved  by  analysis.  Indeed,  analyses  of  the  salts  crystal- 
lized out  on  the  walls  of  the  drifts  showed  all  of  the  bases  and  acids  de- 
tected in  the  water  or  the  ore,  excepting  hyposulphurous  acid,  gold,  and 
nickel.  As  cobalt  was  present  in  two  cases,  nickel  might  doubtless  have 
been  detected  in  traces.  Hyposulphurous  acid  I  suppose  to  result  only 
from  the  oxidation  of  alkaline  sulphides  and  gold  is  present  only  in  very 
minute  quantities  in  the  marcasite.  The  waters  as  they  reach  the  surface 
are  far  from  being  saturated  solutions  of  borax  or  of  alkaline  chlorides,  and 
there  is  no  reason  to  assume  any  tendency  for  the  metallic  bases  detected 
to  decompose  sodium  chloride.  On  the  other  hand,  sulphates  of  the  alkaline 
earths  are  comparatively  insoluble  and  might  be  deposited  with  the  ore. 
Sulphuric  acid  has,  moreover,  constantly  formed  at  the  surface,  diffusing 
downward  to  a  greater  or  less  extent.  It  is  very  likely  that  a  large  part  of 
the  sulphates  now  present  in  the  ores  of  the  surface  workings  have  formed 
since  the  ground  was  broken,  for  the  excavations  have  interfered  with  the 
flow  of  the  water  to  the  lake. 

It  is  plain  from  the  foregoing  that  the  waters  are  capable  of  depositing 
exactly  such  mineral  mixtures  as  the  ores  represent,  with  the  very  impor- 
tant exception  of  the  cinnabar.  The  conclusion  that  the  ores  have  been  de- 
posited from  similar  waters  is  inevitable.  At  the  time  of  deposition  either 
some  slight  variation  in  composition — possibly  the  absence  of  ammonia  — 
enabled  these  waters  to  hold  cinnabar  in  solution  at  ordinary  pressures  or 
they  are  now  capable  of  dissolving  cinnabar  under  somewhat  different 
physical  conditions,  as  was  suggested  above. 

Precipitation  of  the  ore. — The  hypothesis  that  these  waters  under  other  physi- 
cal conditions  would  dissolve  cinnabar  finds  some  support  from  observa- 
tions of  the  circumstances  attending  the  deposition  of  the  ore.  Cinnabar  was 
found  in  the  workings  of  the  Hermann  shaft  several  hundred  feet  below  the 
surface,  and  in  the  open  workings  the  richer  portion  of  the  ore  occurs  in 
part  beneath  the  basalt  and  in  part  in  its  lower  portion.  Above  the  richer 
bodies  comes  a  mixture  of  sulphur  and  cinnabar  and  at  the  original  sur- 
face no  mercuric  sulphide  whatever  was  found.  These  facts  can  hardly  be 


262  QUICKSILVER  DEPOSITS  OF  TUB  PACIFIC  SLOPE. 

accounted  for  by  supposing  that  the  ore  was  precipitated  by  the  sulphuric 
acid  forming  at  the  surface.  The  rock  is  attacked  by  acid  to  a  depth  of  only 
about  twenty  feet,  and  the  richer  ores  are  found  at  lower  levels,  where  no 
evidence  of  the  presence  of  unneutralized  acid  occurs  and  where  the  composi- 
tion of  the  ore  is  substantially  similar  to  that  in  the  deep  workings.  If  the  ore 
had  been  precipitated  by  acidification  of  the  solutions,  it  would  be  mainly 
found  in  the  upper  part  of  the  bank  or  along  the  under  surface  of  the  layer 
of  basalt  which  has  been  bleached  by  acid.  This  is  not  the  case,  and 
hence,  while  acidification  of  the  solutions  would  undoubtedly  have  thrown 
the  quicksilver  down,  other  causes  of  precipitation  must  have  been  at  work, 
and  indeed  must  have  been  the  chief  ones.  The  fact  that  sulphuric  acid 
forms  at  the  surface  is  also  insufficient  to  account  for  the  absence  of  cinna- 
bar from  the  surface,  for  at  Steamboat  Springs,  where  acid  forms  in  the 
same  way  as  at  Sulphur  Bank,  cinnabar  did  reach  the  surface.  The  forma- 
tion of  sulphuric  acid  from  hydrogen  sulphide  is  not  a  rapid  process,  and  in 
springs  from  which  there  is  a  considerable  flow  of  water  neutralization  by  the 
acid  thus  formed  could  take  place  only  to  a  very  short  distance  from  the  sur- 
face. The  resulting  distribution  of  ore  would  also  be  extremely  irregular. 

There  is  indeed  no  proof  that  the  main  period  of  deposition  of  ore  at 
Sulphur  Bank  was  contemporaneous  with  the  chief  deposition  of  sulphur 
and  the  formation  of  sulphuric  acid.  One  might  rather  suppose  that  when 
the  deposition  of  ore  was  progressing  most  actively  the  upward  flow  of 
solutions  and  the  emission  of  gases  were  too  vigorous  to  permit  the  per- 
meation of  the  upper  part  of  the  bank  by  atmospheric  oxygen.  Little 
sulphur  or  sulphuric  acid  would  then  form,  and  only  at  the  surface.  As 
the  activity  of  the  springs  diminished  the  permeation  of  oxygen  would 
increase,  and  the  sulphuric  acid  slowly  formed  at  the  surface  would  have 
an  opportunity  to  diffuse  through  the  rock.  The  sulphur  beds  may  thus 
not  improbably  be  in  the  main  of  later  origin  than  the  ore. 

While  acidification  is  insufficient  to  account  for  the  precipitation  of  the 
ore,  diminution  of  pressure  and  of  temperature  must  certainly  have  taken 
place  as  the  solutions  rose  to  the  surface.  So  far  as  is  known,  too,  these 
causes  may  be  sufficient  to  explain  the  observed  effect,  but  dilution  with 
waters  percolating  from  the  lake  or  from  springs  may  have  contributed  to 
the  result. 


SULPHUR  BANK  MINE.  263 

There  is  no  trace  of  substitution  of  ore  for  the  rock  in  any  part  of  the 
mine.  It  is  true  that  ore  is  sometimes  found  in  the  crevices  of  concentric 
layers  of  decomposed  basalt,  but  it  is  evident  that  these  crevices  have  first 
formed  through  decomposition  and  that  the  cavities  have  subsequently  been 
partially  filled  with  ore,  as  any  other  openings  would  have  be  311.  In  true 
substitution,  the  solution  of  the  substance  of  the  rock  is  a  condition  of  the 
deposition  of  ore  and  the  interchange  takes  place  molecule  by  molecule. 

It  appears  from  the  above  that  no  absolute  evidence  of  the  deposition 
of  ore  at  the  present  time  has  been  reached,  but  that  the  precipitation  of 
cinnabar,  under  some  pressure,  in  the  lower  portion  of  the  ore-bearing 
ground,  is  not  improbably  still  in  progress.1  Professors  Le  Conte  and  Rising 
have  also  expressed  the  opinion  that  ore  deposition  has  not  ceased. 

The  min3._The  surface  mine  at  Sulphur  Bank  is  a  labyrinth  of  excavations 
in  and  below  the  decomposed  layer  of  basalt,  In  a  few  spots  the  workings 
have  passed  through  the  basalt,  and  lake  beds,  carrying  cinnabar  in  greater 
or  less  quantity,  were  found  below  it.  Between  the  Hermann  shaft  and  the  air 
shaft  shown  on  the  map  an  important  ore  body  was  followed  down  for  several 
hundred  feet.  This  body  had  been  worked  out  before  my  examination  and 
only  the  lowest  portion  of  it  was  accessible.  The  small  amount  of  ore  re- 
maining consisted,  as  has  already  been  stated,  of  partially  metamorphosed 
sandstones  and  shales  of  the  Knoxville  group,  carrying  small  stringers  of 
cinnabar,  quartz,  and  pyrite.  The  top  of  the  ore  body  is  said  to  have  been 
in  lake  beds  similar  to  exposures  made  near  by  during  my  visit,  but  I  was 
not  able  to  get  satisfactory  information  as  to  the  depth  from  the  surface  of 
the  contact  between  the  pebble-bearing  lake  deposits  and  the  brecciated, 
metamorphic  sandstones  and  shales.  This,  however,  is  not  a  matter  of  great 
consequence. 

The  underground  mine  consists  of  a  shaft  417  feet  deep,  with  seven 
short  levels.  The  rock  is  everywhere  of  the  Knoxville  group  and  sandstone 
predominates ;  it  is  much  disturbed  and  is  full  of  slickensides,  but  the  prev- 
alent dip  is  to  the  southeast.  No  second  ore  body  of  importance  has  been 
discovered,  though  traces  of  cinnabar  are  common. 

Excepting  for  the  solfataric  springs  the  underground  mine  at  Sulphur 
Bank  resembles  the  other  principal  quicksilver  mines  of  California.  The 

'For  a  confirmation  of  this  deduction,  see  the  addendum  to  this  chapter  (p.  269). 


264  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

same  rocks  are  met  in  other  mines  and  the  gangue  minerals  and  the  relations 
of  these  substances  to  the  vein  rock  are  those  most  usual  in  California. 
This  fact  is  an  important  one,  for  it  proves  that  deposits  indistinguishable 
from  those  found  in  the  Redington,  New  Almaden,  and  other  mines  may  be 
formed  i  n  the  same  manner  as  those  at  Sulphur  Bank,  by  precipitation  from 
hot  springs  of  volcanic  origin. 

Partly,  perhaps,  on  account  of  the  degree  to  which  the  hot  water  and 
foul  gases  interfere  with  mining  operations  the  prospecting  of  this  property 
has  been  neglected,  and  there  is  an  insufficient  opportunity  to  study  the 
structural  relations  of  the  ore  and  the  fissures.  I  can,  however,  see  no 
reason  to  suppose  that  the  deposit  is  exhausted.  A  drift  should  be  run 
through  the  ground  which  shows  solfataric  action  beneath  the  surface  mine 
at  a  depth  of  at  least  200  feet,  and  from  this  gallery  at  least  one  cross-cut 
should  be  driven,  so  that  the  hopeful  ground  would  be  completely  inter- 
sected in  two  directions.  It  would  probably  be  found  that  these  drifts 
would  meet  one  or  more  dikes  of  basalt,  the  direction  of  which  would  mark 
the  main  fissure  system  ;  but  for  some  hundreds  of  feet  from  the  surface  the 
structure  and- the  disposition  of  ore  are  probably  very  irregular,  and  a  sys- 
tem of  straight  drifts  and  cross-cuts  would  be  the  only  thorough  method 
of  exploration. 

The  abandoned  mines  on  Mt.  Konocti  appear  to  have  had  an  origin 
entirely  similar  to  that  of  the  Sulphur  Bank.  Their  chief  interest  is  due  to 
the  fact  that  they  occur  in  andesitic  lavas,  thus  adding  to  the  list  of  differ- 
ent rocks  in  which  cinnabar  in  some  quantity  is  found  and  increasing  the 
probability  that  all  the  cinnabar  is  derived  from  a  single  source. 

Little  Sulphur  Bank   and   Borax   Lake. A  few  lllllldred  feet  tO  the  Cast  of  tllC  UHld 

flat  of  Borax  Lake,  and  just  at  the  edge  of  the  obsidian  area,  is  the  so-called 
Little  Sulphur  Bank.  Here  slight  excavations  only  have  been  made.  These 
show  a  considerable  quantity  of  impure  sulphur,  and  I  was  positively  in- 
formed that  traces  of  cinnabar  had  been  found,  though  not  enough  to 
encourage  further  exploration.  No  water  flowed  from  this  locality  during 
my  visit,  but  the  ground  was  moist  and  hot  in  spots.  It  is  possible  that 
during  some  seasons  hot  water  may  still  find  its  way  to  the  surface  and  drain 
into  Borax  Lake.  Everything  thus  indicates  that  the  locality  is  properly 


BORAX  LAKE.  265 

named  and  that  there  is  here  a  repetition  on  a  small  scale  of  the  phenomena 
of  the  larger  Sulphur  Bank. 

Borax  Lake  is  a  small  and  shallow  sheet  of  water  of  variable  area. 
Professor  Whitney  was  informed  that  in  1  861  it  dried  up  entirely.  The 
examinations  of  the  region  described  in  the  last  chapter  make  it  clear  that 
the  nearly  flat  area  in  which  this  pond  is  situated  was  formerly  covered  by 
the  waters  of  Clear  Lake.  Although  Borax  Lake  receives  the  drainage  of  the 
surrounding  hills,  it  is  still  but  little  elevated  above  the  larger  body  of  water 
From  this  it  is  separated  by  a  low  ridge  mainly  and  perhaps  wholly  com- 
posed of  the  obsidian  and  pumice  described  upon  a  preceding  page. 

The  b'oracic  character  of  the  lake  was  first  detected  by  Dr.  J.  A.  Veatch1 
in  185G.  Later  large  quantities  of  borax  crystals  were  extracted  from  the 
mud  and  borings  were  made  in  the  bottom  with  a  view  to  renewing  the  sup- 
ply, but  in  vain.  Professor  Whitney  very  properly  regarded  this  lake  as 
an  evidence  of  former  volcanic  activity;  but,  to  make  sure  that  the  borax 
was  not  leached  out  of  the  surrounding  declivities  by  rain  and  merely  con- 
centrated here,  I  had  careful  tests  made  of  large  quantities  of  the  meta- 
morphic  rock  and  obsidian.  They  showed  no  borax. 

The  water  of  Borax  Lake  was  analyzed  by  Dr.  Melville,  and  the 
composition  of  one  liter  was  found  to  be  as  follows: 

Grams. 
Silica,  SiO2  0.0109 

Alumina,  Al-O3 0.0029 

Ferrous  carbonate,  FeCO3 0.0056 

Manganous  carbonate,  MnCO3 0.0018 

Calcic  carbonate,  CaCO3 0.0233 

Magnesium  carbonate,  MgCOJ 0.9448 

Soclic  carbonate,  Na-CO3 29.1671 

Calcic  phosphate,  Ca3P-08 0.  0225 

Calcic  sulphate,  CaSO4 0.0204 

Sod ie  sulphate,  NacSO4 0.  1248 

Borax,  Na^B'O7 5.0040 

Sodic  chloride,  NaCl 38.9900 

Potassic  chloride,  KC1 2.2003 

Potassic  bromate,  KBr 0.  0447 

Organic  matter 3.6184 

Carbon  dioxide,  CO3 0. 6H39 

Total 80.8654 

1  Geol.  Survey  California,  Geology,  vol.  1,  p.  98. 


266 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


When  this  analysis  is  compared  with  those  of  the  waters  of  Sulphur 
Bank  it  is  manifest  that  there  is  a  very  close  resemblance.  Taking  into 
consideration  also  that  the  waters  which  must  formerly  have  issued  from 
Little  Sulphur  Bank  flowed  into  Borax  Lake,  it  may  be -considered  absolutely 
certain  that  the  formerly  active  springs  of  Little  Sulphur  Bank  furnished 
the  supply  of  borax  now  practically  exhausted,  and  that  there  will  be  no  re- 
newal of  this  supply  unless  the  Little  Sulphur  Bank  should  again  become 
a  flowing  spring.  To  bore  wells  in  Borax  Lake  is  useless.  Possibly,  how- 
ever, a  hole  bored  into  the  Little  Sulphur  Bank  would  bring  about  a  re- 
newed flow  of  dilute  solution  of  borax,  which  by  concentration  under  the 
hot  summer  sun  in  Borax  Lake  would  yield  the  salt  in  profitable  quantities. 


FIG.  6.  Dendritic  sinter  on  the  chore  of  Borax  Lake. 


Dendritic  sinter. — Along  the  shores  of  Borax  Lake  are  numerous  isolated 
masses  of  calcareous  sinter  (Fig.  6).  They  all  grow  from  the  surface  of  the 
lake  bottom,  but  some  of  them  are  partially  submerged  and  some  stood  at 
the  time  of  examination  many  yards  from  the  actual  edge  of  the  lake.  They 
consist  chiefly  of  calcium  carbonate,  with  small  quantities  of  all  the  sub- 


[UHI7BRSITT) 
Jh 

DENDRITFC  SINTER. 

stances  detected  in  the  water  (excepting  manganese  and  bromine)  and,  in 
addition,  traces  of  cobalt  and  lithium.  They  also  contain  some  organic 
matter  which  evidently  consists  in  part  of  the  pupa  cases  of  insects.  These 
sinter  masses  grow  to  a  maximum  diameteT  of  about  four  feet  and  a  height  of 
about  three  feet.  The  outlines  assumed  resemble  those  of  an  isolated  clump 
of  trees  and  bushes  seen  at  a  distance.  They  appear  to  grow  laterally  as  well 
as  vertically,  and  thus  overhang  the  level,  somewhat  pebbly  ground  upon 
which  they  stand.  Broken  masses  show  a  porous,  sponge-like  structure,  but 
I  detected  no  definite  crystal  forms.  There  appeared  to  be  no  opportunity 
to  trace  out  the  history  of  these  masses,  nor  could  I  detect  any  definite 
nucleus.  When  once  a  small  accretion  of  this  sort  has  started,  it  would 
appear  that  the  spongy  mass  draws  up  the  brine  from  the  moist  ground  and 
affords  an  opportunity  for  the  evaporation  of  the  fluid.  Why  the  masses 
consist  substantially  only  of  calcium  carbonate  is  not  certain;  but  it  seems 
not  improbable  that  when  first  formed  they  contain  a  considerable  excess  of 
this  rather  insoluble  compound,  which  separates  out  in  a  comparatively  pure 
form,  as  is  usual  in  cases  of  slow  crystallization  from  mixed  solutions,  and 
that  they  are  further  purified  by  the  winter  rains.  Though  the  inception 
of  these  masses  has  not  been  traced,  it  is  easy  to  imagine  how  it  might  • 
occur.  Any  small  lump  of  pumice,  fragment  of  wood,  or  other  porous  sub- 
stance partially  immersed  or  lying  upon  the  wet  mud  near  the  edge  of  the 
lake  would  tend  to  accumulate  a  crust  of  salts  upon  its  upper  surface  through 
capillary  attraction  and  evaporation,  and  the  spongy  accumulation  would 
then  continue  to  absorb  the  fluid.  These  sinter  masses  appear  to  answer  to 
some  of  the  tufas  associated  with  the  thinolite  studied  by  Messrs.  King, 
Russell,  and  E.  S.  Dana.  They  are  certainly  still  forming  and  are  all  of 
recent  origin.  If  any  substitution  has  taken  place  in  these  sinters  it  must 
have  followed  almost  immediately  upon  deposition  and  probably  accom- 
panied dehydration.  However  this  may  be,  it  is  an  interesting  and  some- 
what important  fact  that  sinters  composed  substantially  of  calcium  carbon- 
ate can  grow  directly  from  a  fluid  containing  large  quantities  of  sodium 
carbonates  and  borax  and  which  holds  only  small  amounts  of  calcium  car- 
bonate in  solution. 


268  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

Little  Borax  Lake,  at  the  foot  of  Mt.  Konocti,  possesses  a  great  deal  of 
similarity  to  the  larger  body  of  mineral  water  near  Sulphur  Bank.  It  is 
snii.ll  and  shallow  and  frequently  dries  up  entirely.  The  salts  deposited 
are  borates  and  carbonates  of  the  alkalis,  but  no  dendritic  sinter  is  found 
along  its  shore.  Evidences  of  the  volcanic  character  of  this  basin  were 
given  in  the  preceding  chapter,  but  no  active  solfatarism  was  observed. 
There  seems  no  reason  to  doubt,  however,  that  its  origin  is  similar  to  that 
of  the  more  important  Borax  Lake. 

Maggots. — Borax  Lake,  like  many  similar  pools,  is  infested  by  flies,  the 
maggots  of  which  appear  to  be  the  sole  inhabitants  of  the  brine.  Speci- 
mens of  these  insects  were  sent  to  Professor  Riley,  who  states  that  the  larger 
part  of  the  specimens  are  larvae  of  Epltijdra  caltfortvcn  Packard.  The  same 
insect  is  abundant  at  Mono  Lake,  where  the  maggots  are  used  by  the-  In- 
dians for  food.  Some  larger  maggots  were  also  found  in  Borax  Lake,  which 
Professor  Riley  determined  as  belonging  to  the  dipterous  genus  Stratiomys. 


ADDENDUM  TO  CHAPTER  VII. 
SOLUBILITY  OF  CINNABAR  IN  AMMONIACAL  SOLUTIONS. 

As  appears  in  part  from  the  foregoiug  chapter,  repeated  efforts  were  made  to 
detect  mercury  iu  the  waters  of  Sulphur  Bauk,  but  without  success.  Consequently, 
although  the  deposit  is  of  such  a  character  as  to  suggest  very  strongly  that  cinnabar 
is  still  being  formed,  such  a  deposition  could  not  be  definitely  asserted  at  the  time  when 
this  memoir  was  transmitted.  The  absence  of  mercury  from  these  waters  was  not  a 
little  perplexing,  for,  as  will  be  described  in  Chapter  XV,  I  had  found  cinnabar  soluble 
to  a  very  considerable  extent  in  artificial  solutions  not  dissimilar  to  the  waters  of  Sul- 
phur Bauk,  aud  everything  pointed  to  the  conclusion  that  the  ore  of  this  locality  must 
have  been  deposited  from  waters  like  those  which  now  flow  from  it.  These  waters, 
however,  are  ammoniacal,  and  experiments  in  my  laboratory  had  proved  that,  under 
ordinary  conditions,  ammonium  salts  completely  precipitate  cinnabar  from  artificial 
solutions. 

Consideration  of  all  the  circumstances  showed  it  very  improbable  that  the  waters 
had  recently  become  ammoniacal,  and  I  therefore  inferred,  as  was  mentioned  on  page 
200,  that  cinnabar  was  probably  soluble  at  high  temperatures  and  pressures  in  am- 
moniacal waters,  seeing,  also,  in  this  hypothesis  an  explanation  of  the  remarkable 
fact  that  cinnabar  nowhere  appeared  at  the  original  surface  of  the  bank. 

To  test  the  matter  I  devised  certain  simple  experiments,  which  were  carried  out 
after  the  transmission  of  this  volume.  A  solution  of  mercuric  sulphide  was  first  made 
in  a  manner  which  will  be  described  in  detail  in  Chapter  XV.  The  solvent  is  prepared 
by  dividing  a  solution  of  sodic  carbonate  into  two  portions,  saturating  one  of  them 
with  hydrogen  sulphide  and  mixing  the  fluids.  This  liquid  dissolves  mercuric  sulphide 
as  a  double  sulphide  of  mercury  and  sodium.  The  solvent  was  charged  with  mercuric 
sulphide  and  filtered.  Ammonium  carbonate  was  then  added  till  a  large  precipitate 
formed,  and  portions  of  the  mixture  were  sealed  in  glass  tubes,  which  were  about  half 
filled.  These  tubes  were  then  heated  to  various  temperatures  above  100°  C.  At  120° 
the  solutions  still  showed  the  dark  tint  due  to  the  presence  of  unclissolved  sulphide, 
but  at  145°  and  at  175°  the  mercuric  sulphide  was  entirely  dissolved  in  less  than  an 
hour.  On  cooling,  the  black  color  again  appeared,  and  it  was  found  by  appropriate 
tests  that  this  coloration  was  due  to  reprecipitated  mercuric  sulphide. 

Ammonia  in  the  presence  of  hydrosulphurioaud  carbonic  acids  thus  does  not  com- 
pletely precipitate  mercuric  sulphide  at  high  temperatures  and  pressures,  and  waters 

269 


270  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

similar  to  those  of  Sulphur  Bank,  though  incapable  of  dissolving  cinuabar  under  the 
physical  conditions  existing  at  the  surface,  would  hold  it  in  solution  at  higher  tem- 
peratures and  pressures.  Such  waters  rising  toward  the  surface  would  deposit  the 
entire  quantity  of  cinuabar  held  in  solution  before  reaching  the  atmosphere. 

This  discovery  seems  to  furnish  an  entirely  satisfactory  explanation  of  the  absence 
of  cinnabar  from  the  original  surface  of  the  Sulphur  Bank  and  of  the  failure  to  find 
mercury  in  the  water;  It  also  removes  all  reasonable  doubt  that  the  deposits  of  cur- 
dy, hydrous  silica  containing  cinnabar  are  really  as  recent  as  they  appear  and  that 
the  ore  is  still  accumulating  at  this  interesting  locality.  The  experiment  furthermore 
affords  an  actual  instance  of  the  precipitation  of  an  important  ore  by  relief  of  temper- 
ature and  pressure,  a  method  of  deposition  the  evidence  of  which  is  generally  imperfect 
and  indirect. 


CIIAPTKK  VIII. 

DESCRIPTIVE  GEOLOGY  OF  THE  KNOXVILLE  DISTRICT. 

[Atlas  SUeet  V.] 

General  character. — This  district  includes  the  point  at  which  Napa,  Lake, 
and  Yolo  Counties  meet.  It  presents  the  usual  characteristics  of  the  Coast 
Ranges:  low,  rocky  ridges,  partially  covered  by  brush  and  a  scanty  growth 
of  trees  and  divided  by  narrow  valleys.  Though  some  pleasing  views  are 
to  be  had  from  the  higher  points,  the  region  is  not  a  picturesque  one.  It 
possesses  great  geological  interest,  however,  for  it  affords  an  admirable 
opportunity  for  the  determination  of  the  age  of  the  metamorphic  series  and 
for  a  studv  of  the  processes  of  metamorphism.  It  also  contains  a  series  of 
quicksilver  deposits  which  show  instructive  features  and  which  bear  signifi- 
cant relations  to  the  metamorphic  rocks  and  to  basalt. 

The  Knoxviiie  series. —  Tlie  area  embraced  in  the  detailed  map  contains  fos- 
sils at  a  number  of  points,  and  study  of  the  district  shows  that  all  of  the 
sedimentary  beds  are  probably  of  the  same  age,  belonging  to  one  division, 
the  lower,  of  the  Shasta  group  of  Messrs.  Gabb  and  Whitney.  As  has  been 
explained  in  Chapter  V,  it  is  advisable  to  consider  this  series  as  wholly  dis- 
tinct from  the  Shasta  beds  on  Cottonwood  Creek,  in  Shasta  County.  It  is 
characteristically  developed  in  the  Knoxviiie  district,  where  also  it  is  the 
only  series  exposed,  and  Dr.  White  and  I  have  therefore  christened  it  the 
Knoxviiie  group.  The  Knoxviiie  beds  form  a  very  large  part  of  the  Coast 
Ranges  and  of  the  auriferous  slates  of  the  Sierra  Nevada. 

A  considerable  portion  of  the  rocks  in  this  district  are  nearly  or  quite 
unaltered  and  consist  of  predominant  sandstones  interbedded  with  shales 

271 


272  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

and  a  little  impure  limestone.  The  beds  stand  at  many  angles,  but  their 
dip  is  usually  very  high,  while  the  prevalent  strike  is  in  the  direction  of  the 
ranges.  Fossils  are  abundant  at  a  few  points,  but  are  not  very  generally 
disseminated.  By  far  the  most  frequent  and  the  most  important  forms  are 
two  species  or  varieties  of  Amelia.  These  were  not  distinguished  by  Mr. 
Gabb,  who  collected  specimens  here  and  gave  them  the  name  A.  Piochii, 
but  Dr.  White  considers  the  more  robust  form  as  A.  concaitricu  and  the 
more  slender  us  A.  mosquensis.  These  and  the  accompanying  fossils  have 
been  fully  discussed  in  Chapter  V,  and  the  conclusion  was  there  reached 
that  the  beds  carrying  them  are  close  to  the  line  of  division  between  the 
Jurassic  and  Cretaceous  formations,  but  are  probably  to  be  considered  as 
the  earliest  Cretaceous,  and  therefore  as  belonging  to  the  Neocomian  period. 
The  study  of  these  fossils  when  first  collected  led  me  to  the  belief  that  the 
beds  carrying  them  could  not  be  separated  from  the  slates  of  the  gold  belt, 
which  also  carry  AticeUa.  This  conclusion  was  afterwards  fully  confirmed 
by  Dr.  White. 

Mctamorphic  rocks. —  The  Coast  Ranges  are  so  scantily  supplied  with  fossils 
that  the  determination  of  these  beds  and  their  correlation  with  those  of  the 
Sierra  Nevada  are  matters  of  much  interest;  but  of  no  less  interest  is  the 
fact  that  this  district  affords  abundant  opportunities  of  tracing  the  passage 
of  these  beds  into  the  metamorphic  rocks.  The  microscopical  evidence  of 
these  transitions  has  been  set  forth  at  great  length  in  an  earlier  portion  of 
this  memoir,  but  the  structural  relations  have  been  only  briefly  referred  to. 
These  are  of  great  importance  for  two  distinct  reasons.  One  of  them  is 
that  eminent  geologists  deny  that  large  areas  of  ordinary  sediments  are 
converted  into  crystalline  rocks  and  serpentine  by  secondary  processes;  in 
other  words,  they  deny  the  theory  of  regional  metamorphism.  The  second 
reason  for  a  minute  description  of  the  occurrence  is  that  the  results  of  mere 
microscopic  examinations  of  collections  are  not  altogether  trustworthy. 
The  phenomena  which  specimens  and  slides  from  complex  areas  present 
are  so  multifarious  that  it  is  nearly  always  possible  to  draw  various  plausi- 
ble conclusions  from  them.  Specimens  may  often  be  so  arranged  as  to  sup- 
port arguments  either  for  connecting  the  most  diverse  rocks  by  transitions 
or  for  separating  varieties  which  are  in  reality  closely  allied.  When  due 


METAMOEPHIC  ROCKS.  273 

regard  is  paid  to  the  occurrence  in  the  field,  on  the  other  hand,  the  number 
of  possible  hypotheses  is  generally  reduced  to  one. 

There  can  be  no  question  as  to  the  regional  character  of  the  occurrence 
of  crystalline  rocks  at  Knoxville.  A  part  of  the  area  of  the  map,  to  be  sure, 
is  unaltered  rock ;  but  from  the  westerly  edge  of  the  map  westward  the 
crystalline  rocks  and  serpentine  form  an  unbroken  mass  many  miles  in 
width  ;  indeed,  it  would  probably  be  possible  to  proceed  from  Knoxville  to 
the  mouth  of  the  Russian  River,  not  in  a  perfectly  straight  line,  but  with 
no  great  deviations,  without  leaving  this  series. 

The  crystalline  rocks  not  eruptive. —  It  is  equally  certain  that  these  rocks  are  in 
fact  neither  of  igneous  origin  nor  crystalline  precipitates  from  an  ancient 
sea.  No  observer  studying  the  rocks  on  the  ground  could  fail  to  come  to 
this  conclusion;  and,  if  conviction  be  not  brought  home  to  the  reader,  it  will 
be  due  entirely  to  imperfect  description.  No  area  of  more  than  a  few  yards 
can  be  examined  without  revealing  evidence  that  the  rocks  are  stratified. 
It  is  true  that  in  a  large  proportion  of  cases  there  is  entire  discordance  be- 
tween the  planes  of  stratification  of  different  portions  of  a  single  cropping, 
but  fractures  may  often  be  detected  between  adjoining  masses  which  bear 
this  relation,  and  sometimes  distinct  plication  accompanied  by  a  more  or  less 
elaborately  developed  fissure  system  is  apparent.  In  the  granular  and  ser- 
pentinoid  series  no  masses  are  intercalated  which  exhibit  the  common  char- 
acteristics of  eruptive  rocks:  a  lack  of  stratification  and  a  tolerably  persistent 
granular  or  porphyritic  structure.  The  only  rock  in  this  district  possessing 
this  character  is  the  basalt,  which  is  manifestly  far  younger  than  the  strati- 
fied rocks.  It  has  frequently  been  maintained  that  certain  rocks,  like  gneiss, 
which  show  distinct  stratification,  are  of  eruptive  origin.  That  a  gneissoid 
structure  may  be  produced  by  igneous  action,  at  least  over  small  areas,  is 
certain.  I  have  myself  seen  such  a  case  in  New  England.  A  dike  of  some- 
what porphyritic  diabase  filled  a  fissure  in  unstratified  granite,  but  at  one 
point  an  irregularity  in  the  fissure  left  a  mass  of  granite  projecting  into  the 
dike.  This  had  been  softened  by  the  heat  of  the  eruptive  rock  and  molded 
by  the  pressure  of  the  intrusive  material.  It  had  assumed  a  perfectly 
gneissoid  structure  without  being  separated  from  the  wall  of  granular  granite- 
But  when  an  igneous  origin  is  attributed  to  large  areas  of  rock  it  must  at 
MON  xiu  —  18 


274  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

least  be  shown  that  they  possess  a  certain  degree  of  uniformity  ;  for,  though 
there  may  be  gradual  changes  from  point  to  point  in  a  mass  which  has  been 
reduced  to  a  pasty  state  by  imperfect  fusion  and  which  has  been  extruded 
through  vents,  a  certain  degree  of  homogeneity,  more  easily  appreciated 
than  described,  is  inevitable.  This  is  entirely  lacking  in  the  rocks  at  Knox- 
ville,  which  often  change  from  one  structure  to  another  in  the  most  capri- 
cious manner  and  which  frequently  pass  over  into  little  altered,  clastic  rocks. 
Though  there  are  single  specimens  and  blocks  of  rock  which  might  be  sup- 
posed eruptive,  the  greater  part  of  the  rocks  are  not  comparable  with  gneiss 
or  with  any  eruptive  rock  and  are  manifestly  closely  allied  to  sandstones  and 
slates  such  as  no  one  would  think  of  considering  eruptive.  As  has  already 
been  remarked,  no  case  of  interbedded  Pre-Tertiary  eruptives  has  been  met 
with  in  the  investigations  described  in  this  volume  nor  any  instance  ia  which 
the  serpentine  is  eruptive  or  traceable  to  the  alteration  of  an  eruptive  rock. 

These  rocks  not  crystalline  precipitates Tll6  Supposition   that  the  granular  and  S6r- 

peritinoid  rocks,  though  sedimentary  in  their  origin,  were  originally  depos- 
ited in  approximately  their  present  condition  also  requires  careful  consider- 
ation, particularly  as  this  appears  from  the  published  evidence  to  be  the 
most  probable  explanation  of  the  genesis  of*  some  similar  rocks  in  other 
parts  of  the  world.  Were  this  the  case  at  Knoxville,  two  possibilities  would 
present  themselves  :  Either  the  conditions  necessary  to  the  deposition  of  the 
crystalline  rocks  must  have  been  general,  in  which  case  the  ordinary  sedi- 
mentary strata  of  the  district  are  of  a  different  age,  or,  on  the  other  hand,  it 
might  be  that  the  ordinary  sediments  and  the  crystalline  rocks  are  of  the 
same  age  and  that  local  influences  produced  the  differences  in  lithological 
character. 

The  granular  and  serpentinoid  rocks  of  the  Knoxville  district  are  of 
the  same  age  as  the  ordinary  soft,  fossiliferous  sandstones  and  shales,  and 
this  is  shown  independently  by  the  structure  of  the  country  and  by  the 
transitions  between  the  two  classes.  The  structure  can  be  particularly  well 
studied  in  the  neighborhood  of  the  Reed  mine,  on  the  north  branch  of 
Davis  Creek.  To  the  northwest  of  the  mine  lies  an  area  of  unaltered  rocks 
carrying  Ancella  and  other  fossils;  another  and  larger  area,  also  carrying 
,  extends  in  a  southwesterly  direction  from  a  point,  about  one  tlion- 


METAMOBPHIC  ROOKS.  275 

sand  feet  south  of  the  Reed  mine.  To  the  west  of  the  mine,  and  again  to 
the  east  of  it,  are  large  areas  of  serpentinoid  rocks,  which  are  connected  by 
a  neck  a  few  hundred  feet  in  width,  cut  by  the  creek  near  the  mine.  The 
strike  of  the  unaltered  strata  in  both  areas  is  northwesterly,  coinciding  in 
general  direction  with  the  creek,  and  a  large  portion  of  these  strata  are 
inclined  at  high  angles,  most  of  those  in  the  creek  bed  and  a  large  part  of 
those  in  the  southern  area  being  vertical  or  nearly  so.  Had  the  crystalline 
rock,  including  serpentine,  been  deposited  before  or  after  the  ordinary  sand- 
stones and  shales,  and  conformably  with  them,  the  two  unaltered  areas 
would  be  continuous,  instead  of  being  divided  by  an  isthmus  of  crystalline 
rock.  If  the  crystalline  rocks  had  been  first  deposited,  but  disturbed  prior  to 
the  deposition  of  the  sandstones,  so  that  the  latter  were  unconformably  de- 
posited and  afterwards  folded  up,  it  is  difficult,  but  perhaps  not  impossible, 
to  imagine  relations  such  as  those  thus  far  described;  but.  this  hypothesis 
is  entirely  inconsistent  with  another  structural  feature.  The  north  branch 
of  Davis  Creek,  from  below  the  Reed  mine  to  the  northwestern  edge  of  the 
map,  follows  the  axis  of  an  anticlinal  fold,  so  that  the  strata  on  each  side  dip 
into  the  hills.  The  same  structure  is  traceable  to  the  south  also,  particu- 
larly on  Eticuera  Creek  below  the  Redington  mine.  If,  therefore,  there  is 
any  difference  in  age,  the  crystalline  rocks  are  younger  than  the  sandstones 
and  overlie  them.  But  this  is  also  impossible  ;  for,  while  the  sandstones  are 
comparatively  little  broken,  the  crystalline  rocks  show  most  abundant  evi- 
dence of  extremely  violent  disturbance,  and  evidently  the  upper  portion  of 
a  series  cannot  be  crushed  while  the  lower  portion  remains  intact. 

section  on  Davis  creek. — The  following  section  on  the  north  branch  of  Davis 
Creek  was  carefully  worked  out  from  numerous  measured  dips  (Fig.  7).  The 
evidence  of  anticlinal  structure  is  clear,  and,  in  view  of  the  foregoing,  it  is  cer- 
tain that  the  southwestern  side  of  the  anticlinal  fold  consists  of  a  crystalline 
mass,  while  the  northeastern  side  is  composed  of  fossiliferous  sandstones, 
shales,  and  impure  limestones.  Nearer  the  Reed  mine  both  sides  of  the  an- 
ticlinal are  crystalline  and  only  the  highly  compressed  portion  close  to  the 
axis  is  arenaceous. 

Transitions  from  ordinal'}'  sediments  to  crystalline  rocks  are  not  lack- 
ing at  Knoxville.  Some  of  these  are  much  more  striking  under  the  micro- 


276  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

scope  than  in  the  field,  for  many  rocks  which  were  not  suspected  to  be 
anything  but  somewhat  indurated  sandstones  are  shown  by  thin  sections 
to  be  holocrystalline  rocks,  here  called  pseudodiabase  and  pseudodiorite. 
Usually,  indeed,  the  transition  is  somewhat  abrupt,  and  the  rule  is  this: 
So  far  as  evidence  of  crushing  of  the  rock  masses  extends,  these  are  more  or 
less  completely  crystalline,  while,  where  the  rock  preserves  its  continuity, 
it  is  generally  an  ordinary,  more  or  less  indurated  sediment.  The  areas  of 
crushed  rock  are  naturally  well  defined ;  for,  where  the  force  exceeded  the 
cohesion,  the  rock  broke,  but,  where  the  cohesion  exceeded  the  stress,  the 
rock  could  only  be  bent  or  molded.  There  is  no  difficulty,  however,  in 
finding  along  the  edges  of  these  areas  cases  of  partial  conversion  to  crys- 
talline material. 


FIG.  7.  Partly  metamorphosed  anticlinal,  north  fork  of  Davis  Crock. 

The  relations  of  the  crystalline  rock  to  the  anticlinal  structure  on  the 
north  branch  and  to  the  fissuring  of  the  mass  are  so  indicative  that  it  is  al- 
most superfluous  to  consider  the  hypothesis  of  local  crystalline  precipitates. 
This  theory  would  not  exclude  transitions,  but  it  is  difficult  to  imagine  that 
areas  of  crystalline  and  uncrystalline  sedimentation  should  be  so  intimately 
associated  with  each  other;  The  absence  of  fossils  in  the  crystalline  rocks 
would  also  indicate  an  equally  remarkable  distribution  of  areas  fitted  for 
animal  life.  The  intense  dynamical  action  evinced  wherever  the  rocks  are 
crystalline  and  the  absence  of  similar  action  in  the  ordinary  beds  appear 
to  prove  conclusively  that  the  crushing  and  the  crystallization  were  asso- 
ciated phenomena.  The  microscope  finally  shows,  in  connection  with  the 
field  studies,  that  the  crystallization  was  a  secondary  process,  the  progress 
of  which  can  be  followed  in  great  detail. 

serpentine. — The  granular  and  serpentinoid  rocks  cannot  be  sharply  sep- 
arated from  the  unaltered  sedimentary  rocks,  as  has  been  pointed  out  above. 


SERPENTINE.  277 

Still  less  sharp  is  the  distinction  between  the  serpentine  and  the  other  altered 
rocks,  though,  so  far  as  practicable,  the  areas  covered  by  each  are  indicated 
on  the  map  by  different  colors.  There  is  nevertheless  abundant  evidence 
that  serpentinization  was  a  distinct  process  at  Knoxville,  from  the  formation 
of  granular  pseudodiabase,  pseudodiorite,  and  glaucophane  schist,  all  of 
which  were  formed  under  similar  conditions  and  at  the  same  time.  The  ser- 
pentine was  formed  in  part  from  these  granular  rocks,  but  in  part  also  from 
sandstone,  and  the  microscopical  evidence  of  this  fact  has  been  full}7  stated 
in  Chapter  III.  This  would  be  inferred  from  the  occurrence  in  the  field,  but 
the  difficulty  of  distinguishing  partially  altered  sandstones  from  sandstones 
which  have  been  converted  into  fine-grained,  holocrystalline  rocks  is  such 
that  it  would  be  impossible  to  make  absolutely  sure  that  a  preliminary 
recrystallization  did  not  invariably  precede  serpentinization.  In  a  great 
number  of  occurrences  at  Knoxville  serpentinization  has  evidently  begun 
along  cracks  in  rock  retaining  macroscopically  the  appearance  of  somewhat 
altered  sandstone.  When  some  progress  has  been  made  in  the  conversion, 
the  structure  may  be  illustrated  by  the  following  diagram  prepared  from 
sketches.  Here  the  serpentine  is  represented  by  dark  bands  of  nearly  even 
width,  but  the  corners  of  the  intervening  blocks  are  rounded,  and  it  is  evi- 
dent that,  were  the  serpentine  removed,  the  remaining  masses  would  no 
longer  fit  together  as  they  originally  did  (Fig.  8).  When  the  process  has 
been  carried  further  rounded  balls  are  formed  and 
in  some  cases  these  have  weathered  out  and  strew 
the  ground  like  water- worn  pebbles.  The  process  is 
mechanically  strictly  analogous  to  the  formation  of 
balls  of  basalt  in  the  Sulphur  Bank,  of  which  mention 
was  made  in  the  last  chapter,  and  a  theory  of  the 
process  has  been  given  on  page  G8. 

The    fibers   of   serpentine   usually  follow   the 
direction  of  the  veins  separating  the  more  or  less     cracta  in  the  mas8' 
rounded  masses  which  they  include,  but  in  a  few  cases  stand  vertically  to 
the  surfaces  of  the  unserpentinized  nuclei,  and  the  lines  of  division  then 
clearly  mark  the  exact  position  of  the  original  crack,  as  shown  in  Fig.  9. 
One  very  fine  rase  was  found  in  which  a  subangular  mass  when  broken 


278  QUICKSILVER  DEPOSITS  OF  TIIE  PACIFIC  SLOPE. 

open  showed  a  rounded  kernel  of  unserpentinized  rock  within  a  shell  two 
inches  or  more  in  thickness  composed  of  fibers  of  serpentine  standing  per- 
pendicularly to  the  surfaces.  These  phenomena  seem  to  demonstrate  that 

the  conversion  of  other  rocks  to  serpentine  has 
been  effected  by  the  instrumentality  of  solutions 
reacting  on  the  material  of  the  rocks.  The  latter 
are  acid,  and  the  solutions  must  have  been  niag- 
nesian.  Partially  serpentinized  shales  also  occur, 


no. o.  serpentine ^forming from  but  I  have  nowhere  seen  any  tendency  to  the 
normaTto  the  at  tacked*  surface™  formation  of  balls  in  this  rock.  This  fact  indicates 

that  a  portion  of  the  constituents  of  the  shale 

resisted  serpentinization  so  that  replacement  of  the  rock  as  a  whole  could 
not  take  place,  and  only  impregnation  or  the  replacement  of  certain  con- 
stituents was  possible.  Not  a  trace  of  any  olivinitic  rock  could  be  found 
in  Knoxville  or  its  neighborhood,  excepting  the  basalt,  which  is  certainly 
far  more  recent  than  the  formation  of  serpentine  and  has  suffered  little 
decomposition. 

Serpentine  is  attacked  and  removed  by  atmospheric  agencies  about  as 
rapidly  as  partially  altered  sandstones.  Where  croppings  of  the  latter  are 
serpentinized  in  part,  sometimes  the  sandstone  and  sometimes  the  serpentine 
may  be  seen  standing  in  relief.  On  the  whole,  however,  the  serpentine 
appears  to  offer  least  resistance  to  weathering. 

On  the  map  serpentinized  and  unserpentinized  metamorphic  rocks  arc 
laid  down  in  different  colors.  This  division,  however,  must  not  be  taken  as 
absolute.  Traces  of  serpentine  are  to  be  found  in  the  unserpentinized  area, 
and  there  are  many  small  masses  of  other  metamorphic  rocks  in  the  area 
colored  as  serpentinized.  In  the  nature  of  the  case  an  absolute  division  is 
impossible,  but  the  colors  represent  the  limits  within  which  serpentine  is  the 
prevalent  rock  and  serve  to  illustrate  the  approximate  distribution  of  one 
phase  of  metamorphism. 

Chromic  iron  is  found  in  the  serpentine  here,  as  at  many  other  places 
in  the  Coast  Ranges.  At  one  locality,  not  far  from  the  Royal  claim,  it  forms 
a  series  of  nodules  around  which  the  serpentine  has  weathered  away.  The 


NKW  MINERALS.  279 

ore  forms  a  belt  or  seam,  and  a  considerable  quantity  of  it  might  be  obtained 
\\ -<TC  the  material  in  sufficient  demand. 

Redingtonite. —  On  the  150-foot  level  of  the  Redington,  at  a  point  where 
solfataric  gases  still  issue,  a  hydrous  chromium  sulphate  occurs  in  fissures 
in  silicified  serpentine.  This  substance  is  doubtless  the  result  of  the  action 
of  the  gases  upon  chromic  iron.  Qualitative  analysis  showed  that  it  is  a 
hydrous  sulphate  of  chromium,  containing  some  aluminium  and  iron  prob- 
ably replacing  chromium.  The  mineral  is  a  finely  fibrous  mass,  and  some- 
times the  fibers  are  only  just  distinguishable  under  the  microscope.  The 
color  is  pale  purple.  The  aggregates  of  parallel  fibers  sometimes  appeal- 
white,  excepting  on  the  surface  perpendicular  to  the  fibers.  Under  the  micro- 
scope the  mineral  is  colorless,  the  fibers  are  extremely  fine,  arid  no  crystal 
form  is  visible.  The  fibers  possess  double  refraction  and  never  extinguish 
parallel  to  the  nicol  planes.  The  angles  of  extinction  vary  between  13° 
and  38°.  The  crystals  are  therefore  probably  triclinic.  It  seems  appropri- 
ate to  give  the  name  redingtonite  to  this  hitherto  unknown  mineral. 

When  this  mineral  is  heated  it  turns  green  without  losing  all  its  water, 
and  coatings  of  this  green  sulphate  occur  upon  the  redingtonite.  Under 
the  microscope  this  green  sulphate  is  found  to  be  composed  of  rhombic 
tables  with  angles  of  78°  and  102°.  The  cleavage  parallel  to  the  base  is 
excellent,  and  it  also  possesses  good  cleavages  parallel  to  the  prism  faces 
and  to  the  macropinacoid.  It  is  somewhat  pleochroitic,  and  the  color  is 
most  intense  when  the  short  diagonal  is  parallel  to  the  principal  nicol  plane. 
The  refraction  and  the  double  refraction  are  of  medium  strength.  The 
mineral  seems  to  be  isomorphous  with  copiapite.  The  tables  are  too  small 
to  show  the  emergence  of  the  optical  axes ;  but  tests  with  the  mica  foil 
show  that  of  the  two  axes  of  elasticity  lying  in  the  basal  plane  the  one 
parallel  to  the  brachyaxis  is  the  larger.  This  agrees  with  copiapite,  which 
is  negative.  The  detection  of  these  minerals  is  due  to  Mr.  Lindgren. 

siiicification. — There  are  two  distinct  periods  of  silicification  traceable  at 
Kno.xville.  One  of  these  is  represented  by  a  fine  net- work  of  quartzose 
veins  intersecting  a  great  proportion  of  the  metamorphosed  rocks.  Silicified 
shales  or  phthanites  are  particularly  prominent  in  this  respect;  but  altered 


280  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sandstones  and  granular  metamorphics,  as  well  as  some  of  the  serpentinized 
rocks,  show  a  similar  injection.  The  purer  serpentines  are  seldom  inter- 
sected by  quartz  veins,  apparently  only  because  this  rock,  though  soft,  is 
tough  and  not  easily  fissured.  Where  the  net  of  quartz  and  more  or  less 
serpentinoid  rock  coexist,  as  is  the  case  at  many  localities  in  this  district,  it 
seems  certain  that  the  silicification  followed  serpentinization ;  for,  while  the 
angular  fragments  surrounded  by  quartz  veins  are  green,  the  veins  them- 
selves are  not  thus  tinged.  Had  they  existed  prior  to  serpentinization  they 
must  have  been  attacked  like  the  sandstones,  and,  since  the  quartz  veins 
are  permeable  by  solutions,  they  must  have  acquired  a  green  tint.  This 
silicification  is  a  common  characteristic  of  the  metamorphosed  rocks  of  the 
Knoxville  group  throughout  the  Coast  Ranges.  It  is  substantially  coex- 
tensive with  metamorphism  and,  as  explained  in  a  former  chapter,  seems 
to  represent  the  last  phase  of  that  series  of  alteration  processes.  A  more 
intense  and  different  silicification  occurs  at  Knoxville  and  elsewhere  in  the 
neighborhood  of  ore  bodies,  to  which  reference  will  be  made  in  describing 
the  deposits  of  the  district. 

Basalt — The  area  to  be  mapped  was  selected  in  such  a  manner  as  to 
include  all  the  ore  deposits  of  the  neighborhood  and  before  anything  was 
known  of  the  distribution  of  volcanic  rocks.  It  would  almost  seem,  from 
an  inspection  of  the  map,  as  if  the  basalt  area,  which  is  the  only  one  near 
Knoxville,  had  been  purposely  selected  as  the  central  feature.  This  coin- 
cidence is  not  meaningless.  The  basalt  occupies  portions  of  the  crest  and 
flanks  of  a  low  range  of  hills  which  forms  the  boundary  between  Napa  and 
Yolo  Counties.  The  range  itself  is  composed  of  metamorphic  rocks  and  it 
is  evident  from  the  topography  that  the  basalt  forms  a  thin  sheet.  It  is 
altogether  probable  that  the  eruption  of  this  small  basalt  sheet  took  place 
at  two  or  more  points  along  the  crest  of  the  ridge  and  flowed  down  on  both 
sides.  Not  only  does  the  disposition  of  the  rock  answer  to  this  natural 
,  supposition,  but  a  dike  of  the  lava  is  said  to  have  been  met  by  a  tunnel 
from  the  Lake  mine  run  at  right  angles  to  the  crest  jof  the  ridge  from  the 
spot  called  Johntown.  Lithologically  this  basalt  presents  no  peculiarities, 
excepting  that  it  carries  a  rather  small  quantity  of  olivine.  Near  the  basalt 
field  is  a  small  area  of  tufa,  undoubtedly  a  portion  of  the  basaltic  eruption 


BASALT.  281 

which  furnished  some  of  the  building  material  for  the  reduction  furnaces. 
It  is  well  stratified  and  the  beds  are  slightly  inclined,  showing  a  certain 
amount  of  movement  in  the  country  since  its  deposition.  This  tufa  carries 
much  brown  opal  in  the  vertical  cracks  which  intersect  it  in  some  direc- 
tions. 

The  Knoxville  lava  belongs  to  the  older  portion  of  the  series  of 
basaltic  eruptions  of  this  region.  At  one  point  it  shows  remnants  of  what 
was  once  probably  a  crater.  This  and  the  amount  of  erosion  and  weather- 
ing seem  to  refer  it  to  a  date  indistinguishably  near  that  of  the  earlier  por- 
tion of  the  basalts  near  Clear  Lake.  Many  bowlders  have  rolled  from  the 
more  elevated  portions  of  the  basalt  to  lower  ground,  and  the  area  mapped 
as  basalt  probably  includes  a  fringe  of  such  detritus,  through  which  the 
underlying  metamorphics  were  not  visible.  The  basalt  area  is  somewhat 
more  than  two  miles  long. 

All  but  one  of  the  quicksilver  mines  and  prospects  of  the  districts  are 
separated  from  the  edge  of  the  basalt  area  by  distances  of  less  than  half  a 
mile.  The  exception  is  the  Andalusia,  which  lies  nearly  in  the  strike  of  the 
Reed  deposit  and  is  probably  on  the  same  fissure. 

springs. — Near  the  edge  of  the  basalt,  particularly  near  the  Redington 
and  Manhattan  mines,  there  are  numerous  strong  mineral  springs.  These 
springs  are  not  warm,  but  they  carry  so  much  mineral  matter  as  to  produce 
beds  of  sinter  and  to  cement  surface  gravel  into  hard  conglomerates.  The 
sinters  consist  mainly  of  calcium  carbonate.  One  of  them  showed,  in  ad- 
dition to  this  substance,  sodium,  potassium,  lithium,  chlorine,  boracic  acid, 
and  a  very  little  sulphuric  acid.  The  boracic  acid  is  no  doubt  combined 
with  sodium  as  borax,  and  it  is  evident  that  the  water  depositing  this  sinter 
is  closely  analogous  to  that  of  Sulphur  Bank.  This  is  an  important  fact 
when  considered  in  connection  with  other  phenomena  and  will  be  referred 
to  again. 

Deposits  of  the  district. — Three  properties  in  the  district  have  produced  impor- 
tant quantities  of  quicksilver.  These  are  the  Redington,  the  Manhattan,  and 
the  Reed  mines.  At  the  time  of  my  visit  the  best  days  of  these  mines  were 
either  long  past  or  reserved  for  a  remote  future  and  the  greater  part  of  the 
workings  were  entirely  inaccessible.  Only  the  somewhat  extensive  surface 


282  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

workings  of  the  Manhattan  were  open,  the  deep  mine  being  flooded  and  the 
tunnels  caved  in.  At  the  Reed  mine  only  trifling  quantities  of  ore-bearing 
ground  were  to  be  seen  at  the  surface.  Even  in  the  Redington,  which  was 
being  worked,  the  upper  levels  were  for  the  most  part  closed.  The  expos- 
ures nevertheless  reveal  many  important  facts.  Before  taking  up  the  Red- 
ington such  data  as  were  procurable  with  reference  to  the  other  deposits 
may  be  recorded. 

The  Manhattan. — The  Manhattan  and  Lake  mines,  which  are  contiguous 
claims,  lie  to  the  south  of  the  basalt  area.  It  is  somewhat  remarkable  that 
scarcely  a  trace  of  serpentine  exists  near  these  mines.  The  surface  soil  here 
and  also  near  the  Redington  mine  contains  cinnabar,  resulting  from  the 
erosion  of  croppings,  and  accompanying  the  cinnabar  is  free  gold,  which 
may  be  found  by  panning  the  soil.  There  is  no  doubt  that  a  part  of  this 
gold,  if  not  the  whole  of  it,  was  originally  contained  in  pyrite.  No  consid- 
erable workings  are  accessible  upon  the  Lake  property.  A  tunnel  was  run 
from  Johntown  to  the  northeast  underneath  the  basalt,  but  at  the  time  of  my 
visit  it  was  unfortunately  caved  in.  The  watchman,  an  old  miner,  assured 
me  that  a  dike  of  basalt  crossed  this  tunnel  and  that  cinnabar  was  found 
at  the  contact  between  the  lava  and  the  inclosing  rock.  There  is  no  reason 
to  doubt  this  interesting  statement,  for  two  deposits  of  precisely  this  kind 
exist  in  Pope  Valley  and  will  be  described  in  Chapter  XIII.  Stibnite 
occurs  on  this  claim  near  cinnabar.  Mr.  Goodyear  also  found  these  minerals 
associated  on  the  Manhattan  claim.  It  may  be  noted  that  the  same  associa- 
tion is  found  in  the  Stayton  mines,  in  San  Benito  County,  as  well  as  on  the 
Island  of  Corsica,  at  Smyrna,  and  elsewhere. 

The  surface  workings  of  the  Manhattan  are  quite  extensive  and  are  ac- 
cessible, but  the  underground  developments  cannot  now  be  inspected.  This 
mine  has  yielded  about  5,000  flasks  of  metal.  The  open  cuts  are  in  in- 
tensely silicified,  thin-bedded,  and  considerably  disturbed  strata,  There  can 
be  no  doubt  that  a  large  portion  of  the  silicification  visible  here  attended 
the  deposition  of  ore,  but  examination  of  the  surrounding  country  shows 
that  prior  to  the  ore  deposition  the  prevailing  Post-Neocomian  metamorphism 
was  also  of  the  siliceous  type.  It  is  not  possible  to  distinguish  in  detail  how 
much  of  the  silica  was  deposited  in  each  of  the  periods,  but  the  opal  at  least, 


THE  MANHATTAN.  283 

of  which  the  open  cut  shows  large  quantities,  is  referable  almost  beyond  a 
doubt  to  the  period  of  ore  formation.  So  far  as  I  have  observed,  the  silica 
deposited  during  the  regional  metamorphism  is  wholly  crystalline. 

The  silicification,  though  very  intense,-lms  not  obliterated  stratification, 
and  fine  exposures  of  contorted  strata  converted  into  nearly  pure  silica  may 
be  seen.  Vein-like  seams  often  cross  the  strata,  and  in  these,  as  well  as  in 
the  partings  behveen  the  strata,  cinnabar  has  been  deposited  in  brilliant 
contrast  to  the  white  background.  It  is  easy  to  gather  fine  specimens  of 
cinnabar  on  the  exposed  faces,  but  the  average  contents  of  the  material 
exposed  is  certainly  very  low.  Pyrite  accompanies  the  ore,  and  copper 
stains  were  observed,  no  doubt  resulting  from  the  decomposition  of  chalco- 
pyrite. 

prospects — The  Royal  and  the  Grizzly  claims  are  prospects  upon  which 
Tittle  work  has  been  done.  They  belong  to  a  type  which  is  very  prevalent 
in  the  quicksilver  belt.  The  inclosing  rock  is  highly  rnetamorphic  and  very 
heterogeneous,  but  in  the  immediate  neighborhood  of  the  ore  it  is  strongly 
silicified,  and  much  of  it  is  converted  into  a  black  chalcedony  consisting 
chiefly  of  opal.  In  these  claims  the  cinnabar  occurs  to  some  extent  as  im- 
pregnations in  partially  metamorphosed  sandstone,  but  for  the  most  part  in 
threads  and  seams,  either  crossing  or  following  the  bedding,  in  short,  wher- 
ever the  disturbance  preceding  the  deposition  of  ore  left  openings  into  which 
the  solutions  could  penetrate.  It  is  highly  probable  that  deposits  like  these 
might  become  more  regular  below,  but,  so  far  as  these  particular  deposits 
are  concerned,  the  quantity  of  ore  at  the  surface  is  not  sufficient  to  justify 
the  expectation  of  rich  developments  beneath.  Pyrite,  quartz,  and  bitumen 
accompany  the  ore. 

The  Reed  mine. — The  Iveed  mine,  belonging  to  the  California  Quicksilver 
Mining  Company,  is  on  the  north  fork  of  Davis  Creek  and  has  produced, 
according  to  Mr.  Randol's  figures,  5,653  flasks  of  metal.  It  has  not  been 
worked  for  some  years  past.  It  lies  close  to  the  line  which  divides  an  area 
of  serpentine  from  unaltered,  fossiliferous  rocks.  Mr.  T.  J.  Hall,  the  last 
superintendent,  informs  me  that  the  ore  was  followed  from  the  surface  to 
the  300-foot  level,  the  deepest  in  the  mine.  The  trend  of  the  deposit  was 
the  same  as  that  of  the  strata  in  this  neighborhood,  nearly  parallel  to  the 


284  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  8LOPK. 

course  of  the  creek,  and  the  dip  was  30°  to  the  southwest,  which  is  some- 
what less  than  the  average  dip  of  the  disturbed  strata  hereabout.  A  very 
large  part  of  the  ore  of  this  mine  was  metacinnabarite,  as  was  the  case  in 
the  upper  portion  of  the  Redington.  Pyrite  accompanied  the  cinnabar  in 
a  quartzose  gangue  and  some  bitumen  occurred.  The  only  accessible  por- 
tion is  an  open  cut  at  the  croppings.  Here  are  exposed  both  serpentine  and 
the  black  opaline  mass  often  called  "quicksilver  rock"  in  tliis  region.  The 
contact  between  the  two  is  vertical  and  is  pretty  sharp,  but  the  resemblance 
in  general  structure  and  the  appearance  along  the  dividing  line  led  me  to 
the  belief  that  the  opaline  mass  was  an  alteration  product  of  the  serpentine. 
Microscopical  study  has  since  shown  that  both  in  this  district  and  elsewhere 
this  transformation  occurs,  while  other  rocks  as  well  as  serpentine  are,  seem- 
ingly more  rarely,  converted  into  opal.  The  black,  opaline  mass  at  the  Reed 
mine  contains  much  pyrite,  and  the  decomposition  of  this  mineral  appears 
to  have  yielded  salts  capable  of  attacking  the  opal  superficially.  The  cut 
afforded  no  opportunity  for  the  study  of  ore  in  place. 

The  Andalusia  mine  is  in  a  similar  position  to  the  Reed  and  near  the 
same  contact.  The  rocks  at  this  point  have  been  very  considerably  decom- 
posed, apparently  as  a  consequence  of  the  oxidation  of  pyrite.  There  are 
large  quantities  of  black  opal  here,  and  some  of  this  contains  a  considera- 
ble amount  of  microscopic  millerite  —  nickel  sulphide. 

vein  of  cinnabar. — Near  the  furnaces  of  the  Redington  Company  a  prospect- 
ing shaft  was  sunk  for  some  distance  upon  a  little  seam  of  ore,  which  proved 
of  no  value,  but  of  considerable  interest.  The  deposit  formed  a  vein  an 
inch  or  two  in  width,  cutting  the  strata  of  unaltered  Neocomian  sandstone. 
The  fissure  was  filled  with  attrition  material  from  the  walls,  cinnabar,  and 
pyrite.  This  occurrence  is  in  strong  contrast  with  the  other  and  more  im- 
portant deposits  of  the  district,  but  is  no  doubt  coeval  witli  them  and  a 
consequence  of  the  same  set  of  causes. 

THE   REDINGTON. 

Rocks  and  minerals. — This  mine  Avas  discovered  in  making  cuttings  for  a 
county  road.  It  has  been  worked  since  1862  and  lias  produced  nearly 
100,000  flasks  of  metal,  or  more  than  any  other  mine  in  the  State,  except- 


REDINGTON  MINE.  285 

ing  the  New  Almaden  and  the  New  Idria.  The  ore  found  at  the  surface 
was  the  superior  portion  of  an  immense,  irregular  ore  body,  which  con- 
tained far  the  larger  portion  of  all  the  ore  which  the  mine  has  hitherto 
yielded  ;  but  downward  continuations  of  this  body  of  a  much  more  regular 
character  have  been  traced  for  several  hundred  feet.  This  change  in  the 
iorm  of  the  deposit  is  an  extremely  interesting  and  important  feature  of  the 
occurrence. 

The  rocks  immediately  inclosing  the  Redington  mine  are  highly  meta- 
morphic  and  consist  largely  of  serpentine,  which  is  accompanied  by  sili- 
ceous rocks  and  shales,  as  well  as  by  a  great  amount  of  dark,  impure  opal. 
Close  to  the  deposit,  however,  and  in  contact  with  it  at  one  point,  is  a  con- 
siderable area  of  unaltered  sandstone  and  shale.  The  strike  of  the  deposit 
is  also  the  trend  of  the  contact.  The  metamorphic  rocks  surrounding  the 
ore  are  far  too  much  disturbed  and  altered  to  allow  of  any  elucidation  of 
their  stratigraphical  position. 

In  the  upper  and  richer  portion  of  this  mine  a  large  part  of  the  mer- 
cury was  in  the  form  of  metacinnabarite  or  black  sulphide,  which  Dr.  G.  E. 
Moore  first  described  from  this  locality.  Metacinnabarite,  as  already  men- 
tioned, existed  abundantly  at  the  Reed  mine.  Mr.  Goodyear  also  observed 
it  at  the  Baker  mine,  between  Knoxville  and  Lower  Lake.  It  was  found  in 
large  quantities  at  New  Idria,  and  I  have  in  Chapter  II  called  attention  to 
its  occurrence  in  New  Zealand,  Mexico,  and  Rhenish  Bavaria.  So  entirely 
had  the  accessible  portions  of  the  upper  levels  of  the  Redington  mine  been 
worked  out  at  the  time  of  my  visit  that  I  was  unable  to  find  any  of  this 
ore  in  place.  Specimens  show  that  it  was  accompanied  by  opal  and  mar- 
casite  and  that  it  was  in  some  cases  coated  with  cinnabar,  as  if  in  process 
of  conversion.  It  contains  some  iron.  Dr.  Moore's  metacinnabarite  was 
amorphous,  but  according  to  Mr.  Goodyear  it  also  occurred  in  a  crystalline 
state.  Dr.  E.  F.  Durand  describes  crystals  of  this  mineral  which  he  regards 
as  orthorhombic.1  Onofrite  has. been  reported  from  the  Redington,  but 
there  is  little  doubt  that  the  mineral  supposed  to  be  onofrite  was  in  fact 
metacinnabarite.  I  was  informed  that  more  or  less  cinnabar  always  accom- 
panied the  black  ore.  The  two  were' certainly  mingled  at  New  Idria. 

'Proc.  California  Acad.  Nat.  Sci.,  vol.  4,  1872,  p.  211). 


28(5  .   QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Pyrite  and  marcasite  accompany  the  ore  of  the  Redington.  The  pyr- 
ite  was  tested  for  gold  in  my  laboratory  and  unmistakable  reactions  for  it 
were  obtained.  Millerite  occurs  in  microscopic  crystals  in  slides  of  the  ore, 
but  not,  so  far  as  known,  in  masses  recognizable  macroscopically.  The 
gangue  minerals  are  quartz  and  carbonates,  and  vast  quantities  of  opal, 
usually  dark  brown  or  black,  but  sometimes  of  lighter  colors,  are  closely 
associated  with  cinnabar.  Microscopical  examination  shows  that,  while 
pyrite  is  frequently  directly  embedded  in  the  opal,  cinnabar  is  as  a  rule  de- 
posited with  crystalline  silica;  indeed  no  case  was  found  in  which  the  cin- 
nabar was  directly  embedded  in  opal. 

The  black  opal,  locally  known  as  quicksilver  rock,  is  manifestly  a  re- 
sult of  silicification,  which  formed  a  part  of  the  series  of  chemical  changes 
attending  the  deposition  of  ore.  It  was  not  a  phase  of  the  regional  meta- 
morphism  of  the  country,  but  a  local  phenomenon.  It  seems  here  and  else- 
where to  have  preceded  ore  deposition  by  a  short  interval.  The  opal  was 
certainly  not  deposited  in  open  cavities  to  any  considerable  extent,  and  for 
the  most  part  has  replaced  constituents  of  rock  masses  particularly,  but  not 
exclusively,  serpentine.  In  the  Redington  mine,  ore  is  sometimes  found 
with  the  quicksilver  rock  and  sometimes  at  short  distances  from  it,  but  the 
two  substances  are  never  far  apart. 

Although  the  occurrence  of  opal  in  this  and  other  mines,  as  well  as 
microscopical  examinations  of  the  material  which  will  be  described  in  Chap- 
ter XIV,  shows  that  hydrated  silica  replaced  rocks,  cinnabar  seemed  to  me 
to  be  confined  to  fissures,  sometimes  formed  in  opalized  rocks  and  some- 
times in  other  materials.  Cinnabar  occurs  in  contact  with  serpentine,  but 
only  where  there  has  been  disturbance  prior  to  its  deposition,  and,  so  far  ;is 
I  know,  never  under  conditions  indicating  replacement.  The  ore  is  not 
more  usually  found  in  contact  with  one  rock  than  with  another,  but  the 
larger  ore  bodies  seem  most  often  associated  with  brittle  rocks. 

Bituminous  matter  is  not  infrequent  in  this  mine,  and  Dr.  E.  F.  Durand 
has  described  a  volatile  substance  which  occurs  here  and  at  New  Almaden 
as  aragotite,  a  substance  which  he  thinks  allied  to  idrialite.1 

.  California  Aeuil.  Nat.  Sci.,  vol.  4,  187-2,  p.  218. 


UNIVERSITY 


SOLFATARISM  IN  THE 

solfataric  gases. — At  one  point  on  the  150-foot  level,  in  an  old  stope,  the 
temperature  is  high  and  pungent  sulphurous  odors  are  very  noticeable.  At 
this  place  acicular  sulphur  crystals  also  form  upon  the  timbers.  I  am  una- 
ble to  explain  this  occurrence  except  upon  ihe  supposition  that  sulphurous 
acid  and  hydrogen  sulphide  are  escaping,  and  by  their  mutual  decompo- 
sition yield  sulphur.  It  is  not  infrequently  the  case  in  mines  that  hydro- 
gen sulphide  is  produced  by  the  reducing  action  of  timber  upon  soluble 
sulphates,  and  the  oxidation  of  this  gas  may  then  yield  sulphur;  but  I  do 
not  know  of  any  reaction  by  which  sulphurous  acid  can  be  evolved  at  mod- 
erate temperatures  from  soluble  sulphates  in  contact  with  organic  matter. 
The  presence  of  sulphites  or  hyposulphites  among  the  mine  deposits  might 
lead  to  the  evolution  of  sulphurous  anhydride;  but,  while  such  salts  appear 
to  form  near  the  surface  at  Steamboat  Springs  and  Sulphur  Bank,  I  have  met 
with  no  evidence,  there  or  elsewhere,  of  their  deposition  at  depths  such  as 
to  preclude  the  oxidizing  action  of  the  atmosphere  upon  alkaline  sulphides. 
Hence  it  seems  possible  to  account  for  the  sulphurous  anhydride  which 
reaches  the  150-foot  level  of  the  Redington  only  on  the  supposition  that  it 
represents  a  feeble  remnant  of  solfataric  action.  The  only  other  instance 
known  to  me  in  which  sulphur  is  similarly  crystallized  on  timber  is  at  some 
of  the  workings  of  the  Sulphur  Bank  which  are  now  abandoned.  In  that 
case  there  is  no  question  that  the  sulphur  is  produced  by  the  mutual  decom- 
position of  sulphurous  acid  and  hydrogen  sulphide  of  solfataric  origin. 
The  high  temperature  of  the  spot  where  the  sulphur  crystals  were  found 
at  Knoxville  also  strongly  suggests  volcanism.  I  have  no  record  of  this 
temperature,  but  I  am  certain  that  it  considerably  exceeded  100°F.  No 
work  was  progressing  near  the  spot,  so  that  the  abnormal  temperature  was 
not  ascribable  to  candles  and  bad  ventilation.  The  evolution  of  heat  was 
tolerably  rapid,  for  the  locality  was  not  closed  off  from  the  other  workings. 
The  high  temperature  must  have  been  due  either  to  volcanic  emanations  or 
to  local  chemical  action.  The  heat  of  the  Comstock  mines  has  been  hypo- 
thetically  ascribed  to  local  chemical  action,  but  the  hypothesis  is  not  borne 
out  for  those  mines  either  by  observation  or  by  experiment,  and  I  know  of 
no  case  in  which  such  a  temperature  as  that  in  the  Redington,  under  similar 
conditions  of  ventilation,  has  been  clearly  traced  to  local  decomposition  of 


288  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC!  SLOPE. 

minerals.  Were  this  a  case  of  local  chemical  action,  one  would  expect  to 
find  similar  instances  in  other  parts  of  this  mine  and  in  the  other  quick- 
silver mines  of  the  slope,  but,  excepting  at  Sulphur  Bank  and  at  Steamboat 
Springs,  no  such  temperature  has  been  observed  elsewhere.  It  is  clear  that 
this  unusual  temperature,  together  with  the  nature  of  the  occurrence  of  the 
sulphur,  points  to  the  deposition  of  the  ore  from  volcanic  emanations  and  at 
a  comparatively  very  recent  period. 

structure — The  upper  portion  of  the  mine  formed  an  immense  ore  body, 
or,  more  strictly,  a  confused  group  of  ore  bodies,  each  irregular  in  shape 
and  divided  from  the  rest  by  thin  layers  of  poor  or  barren  rock.  The 
lower  portion  of  this  great  ore  body  passed  over  into  two  parallel  veins 
dipping  at  a  high  angle.  These  veins  carried  considerable  quantities  of  ore, 
which  did  not  indeed  extend  continuously  along  the  fissures,  but  occurred 
in  lenticular  masses  at  the  fissures.  The  veins  also  often  showed  thin 
seams  of  ore  where  there  was  no  sufficient  accumulation  to  permit  of  stop- 
ing.  Slickensides  and  clays  were  abundant  along  the  veins.  They  carried 
ore  as  far  as  explored,  to  the  600-foot  level,  but  at  that  depth  no  valuable 
body  of  ore  was  found.  The  relations  of  the  upper  mass  to  the  veins  led 
me  to  believe  that  a  third  fissure  must  exist  in  the  foot-wall,  and  at  my 
suggestion  a  drift  was  run  in  to  the  position  which  the  structure  seemed  to 
indicate  as  the  probable  position  of  such  a  third  vein.  A  fissure  was  found, 
but  at  the  point  where  it  was  struck  it  carried  only  pyrite.  The  ground 
was  very  hopeful  in  appearance,  but  the  affairs  of  the  mine  were  suffering 
greatly  from  the  depression  in  the  quicksilver  market  and  the  exploration 
was  not  pursued. 

The  following  figure  illustrates  a  cross-section  of  the  Redirigton  mine, 
showing  the  relation  between  the  great  ore  deposit  near  the  surface  and  the 
more  deep-seated  fissures  (Fig.  10).  An  accident  having  unfortunately  hap- 
pened to  the  original,  this  figure  is  not  drawn  to  scale,  but  is  founded  on  a 
carefully  prepared  section  to  scale  made  from  the  mine  maps,  supplemented 
by  data  furnished  by  the  foremen  of  the  mine. 

It  is  clear  that  faulting  has  taken  place  at  the  Redington  under  a  com- 
pressive  strain,  the  result  at  lower  levels  being  the  distribution  of  the  move- 
ment over  a  series  of  parallel  planes.  This  is  ;i  phenomenon  which  I  have 


SECTION  OF  THE  EEDINGTON. 


289 


studied  on  former  occasions.1  In  tins  case  the  movement  lias  taken  place 
close  to  the  junction  of  two  rock  masses,  one  metamorphosed,  the  other 
unaltered,  which  offered  different  degrees  of  resistance.  The  motion  also 
took  place  along  a  line  upon  which  violent  disturbance  had  occurred  at  the 
epoch  of  metamorphisin  long  before  the  eruption  of  basalt.  Thus  the 
usual  tendency  to  renewed  motion  along  old  lines  of  movement  is  once 
more  illustrated. 


Flo.  10    Diagrammatic  vertical  cross-section  of  the  Redington  miuo.     in,  metamoiphic;  nt  unaltered  Neocomian rocks. 

In  the  upper  part  of  the  mine  the  disturbance  broke  the  rock  into  a 
confused  jumble  of  fragments.  It  is  difficult  to  imagine  how  this  difference 
of  structure  at  different  levels  can  have  been  produced,  unless  the  present 
surface  is  but  little  beneath  the  surface  as  it  existed  when  the  fissures  were 
formed.  In  other  words;  the  lack  of  system  in  the  fissures  of  the  upper 
mine  is  an  evidence  that  the  fractures  are  comparatively  recent  and  that 
the  rock  near  the  surface  was  thrown  into  confusion  because  it  was  not 
held  in  place  by  superincumbent  masses. 

Age  and  genesis — The  evidence  as  to  the  age  find  the  mode  of  genesis  of  this 
important  deposit  consists  in  a  number  of  facts,  each  of  which,  if  taken 
singly,  maybe  inconclusive,  but  all  of  which  are  concurrent.  It  maybe 
well  to  mention  them  together.  The  deposits  of  the  district  are  grouped 

'Geology  of  the  ConistocU  Lode,  Mou.  U.  S.  Geol.  Survey  No.  3,  chap.  4  ;  Am.  Jour.  Sci.,  3d  series, 
vol.  30,  1685,  pp.  llfi,.  194. 

MON   XIII 19 


290  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

around  the  basalt  area  in  a  manner  which  indicates  a  relation  between  ore 
deposition  and  the  eruption.  At  Mt.  Amiata,  in  Tuscany,  also,  cinnabar 
deposits  occur  along  the  edges  of  a  field  of  lava  and  are  younger  than  the 
eruption.  There  is  information,  believed  to  be  trustworthy,  that  cinnabar 
in  the  Lake  mine  was  deposited  at  the  contact  between  a  basalt  dike  and 
the  inclosing  rock,  and  therefore  later  than  the  basalt.  Mineral  springs 
still  issue  close  to  the  basalt  and  deposit  sinter,  the  composition  of  which  is 
similar  to  that  of  the  matter  held  in  solution  by  the  hot  springs  at  Sulphur 
Bank.  The  Redington,  Reed,  and  Andalusia  mines,  with  the  fissure  from 
which  the  basalt  issued,  form  a  nearly  straight  line.  There  can  scarcely  be 
a  doubt  of  the  escape  of  hot  solfataric  gases  into  the  workings  of  the  Reding- 
ton, and  the  structure  of  the  Redington  ground  is  such  as  seems  readily  ex- 
plicable if  the  ore  has  been  deposited  at  a  time  so  recent  that  little  erosion 
has  since  taken  place,  but  very  difficult  of  comprehension  on  any  other  sup- 
position. These  facts  seem  to  me  to  warrant  the  conclusion  that  the  cinna- 
bar deposits  were  consequences  of  the  basalt  eruption  and  that  the  course  of 
deposition  was  entirely  similar  to  that  of  Sulphur  Bank. 

This  conclusion  is  particularly  important  because  of  the  existence  of 
most  unmistakable  veins  at  the  Redington  mine.  The  upper  part  of  the 
deposit  corresponds  to  and  greatly  resembles  the  underground  developments 
of  Sulphur  Bank.  The  lower  workings  at  Knoxville  develop  typical  veins, 
which  are  continuous  with  the  stockworks  near  the  surface.  The  two  forms 
of  deposit,  which  are  also  associated  at  the  great  Austrian  mine,  were  here 
formed  at  the  same  time  and  by  the  action  of  hot  sulphur  springs.  True 
veins  of  ore  may  then  be  deposited  from  hot  spring  waters.  It  also  follows 
that  true  veins  probably  underlie  the  Sulphur  Bank. 

Future  prospects. — At  the  time  of  my  examination  the  Redington  showed 
little  ore.  This  seemed  to  me  very  largely  due  to  insufficient  prospecting. 
I  do  not  think  a  great  ore  body  such  as  that  at  the  surface  will  ever  again 
be  met  in  this  mine,  but  I  have  no  reason  to  suppose  that  it  is  exhausted 
or  that  important  masses  of  ore  are  not  still  to  be  found  at  or  near  the  prin- 
cipal fissures. 


CHAPTER  IX. 

DESCRIPTIVE  GEOLOGY  OF  THE  NEW  IDRIA  DISTRICT. 

[Atlas  Sheet  VI.*] 

surroundings. — New  Idria  lies  close  to  tile  line  dividing  Fresno  and  San 
Benito  Counties,  among  the  highest  peaks  of  this  portion  of  California. 
These  form  the  southern  end  of  the  Mt.  Diablo  Range  and  divide  the  upper 
waters  of  the  San  Benito  River  from  the  drainage  area  of  the  San  Joaquin. 
The  scenery  of  this  district  is  remarkable  and  wild.  From  its  higher  points 
the  view  is  very  extensive,  embracing  a  large  portion  of  the  Coast  Ranges, 
great  areas  of  the  San  Joaquin  Valley,  and  beyond  it  the  southern  portion 
of  the  snow-capped  Sierra.  To  the  southwest,  the  country  visible  from  the 
New  Idria  peaks  is  fairly  well  watered,  the  ranges  are  wooded,  and  grassy 
meadows  abound  in  the  valleys.  Near  the  crest  of  the  range  also  there  is 
a  respectable  growth  of  trees,  but  the  comparatively  lofty  mountains  of  the 
district  seem  to  extract  the  last  available  portion  of  moisture  from  the  sea 
breezes,  and  the  region  to  the  east  of  New  Idria  is  for  the  most  part  a  wilder- 
ness, where  the  few  springs  are  so  alkaline,  even  in  the  wet  season,  that  cattle 
will  scarcely  touch  them  and  where  a  scanty  growth  of  herbaceous  'plants 
among  the  almost  naked  rocks  appears  only  for  a  few  weeks  in  the  spring. 

This  barren  region  extends  as  far  as  the  San  Joaquin  Valley,  which  is 
fertile,  at  least  in  years  of  plentiful  rain-fall,  and  early  in  the  season  is  gor- 
geous with  wild  flowers.  The  eschscholtzia  often  grows  in  such  masses  in 
the  valley  that  its  fine  orange  tint  is  readily  recognizable  at  a  distance  of 
30  miles  and  stands  out  in  pleasing  contrast  to  the  gleaming  snows  of 
the  Sierra,  which  looms  up  in  a  somewhat  unsubstantial  fashion  125  miles 

291 


292  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

away.  Even  within  the  small  area  embraced  in  the  map  the  diversity  of 
aspect  is  striking.  The  southwestern  portion  of  the  area  surveyed  is  com- 
posed of  highly  metamorphosed  rocks,  crumpled  and  dislocated  out  of  all 
semblance  of  regularity  and  weathered  into  more  or  less  fantastic  forms. 
Except  where  the  surface  is  occupied  by  pure  serpentine,  this  area  supports 
fairly  developed  trees.  To  the  northeast  long  and  high  sandstone  bluff;; 
succeed  one  another  in  endless  succession  and,  being  in  large  part  utterly 
bare  of  vegetation,  show  to  the  most  casual  glance  that  they  are  composed 
of  strata  striking  in  a  direction  parallel  to  the  trend  of  the  range  away  from 
which  they  dip  at  large  angles. 

Questions  presented. — New  Idria  has  been  a  large  producer  of  quicksilver, 
and  was  of  course  selected  for  study  on  that  account.  The  geological  inter- 
est, however,  is  not  confined  to  the  occurrence  of  ore,  for  the  district  happens 
to  be  admirably  suited  to  the  elucidation  of  two  most  important  problems 
in  the  geology  of  the  Pacific  Coast  These  are  the  stratigraphical  relations 
between  the  Lower  and  Upper  Cretaceous  and  the  true  character  of  the 
famous  Toj'on  beds.  The  last  question  has  been  a  subject  of  controversy 
for  a  quarter  of  a  century. 

The  metamorphic  series. — The  metamorpluc  belt,  a  part  of  which  is  included 
in  the  map  of  New  Idria,  is  almost  if  not  quite  continuous  from  Mt.  Diablo 
southward.  The  lithological  and  physical  character  of  the  metamorphic 
rocks  at  New  Idria  is  identical  with  that  of  the  altered  strata,  at  Mt.  Diablo, 
at  Knoxville,  at  San  Luis  Obispo  and,  in  short,  at  all  the  points  where 
members  of  this  series  have  been  found  to  contain  characteristic;  fossils. 
Wherever  determinable  fossils  have  been  found  in  the  metamorphic  se- 
ries— and  localities  are  known  in  nine  counties — the  age  is  the  same,  viz, 
the  earliest  portion  of  the  Cretaceous  period.  No  beds  older  than  this 
are  known  to  exist  in  the  Coast  Ranges.  At  New  Idria  organic  remains 
are  not  altogether  wanting  in  the  rocks  of  this  series,  for  plant  remains  are 
found  in  the  New  Idria  mine,  but  the  specimens  are  far  too  imperfect  to 
admit  of  identification.  Nevertheless  the  facxs  adduced  above,  together 
with  other  general  considerations  enlarged  upon  in  Chapter  V,  make  it  al- 
most certain  that  these  rocks  are  members  of  the  Knoxville  series.  There 
is  a  bare  possibility,  which  no  observed  facts  support,  that  they  may  be 


METAMOBPHIC  HOCKS.  293 

Pre-Cretaceous;  but,  even  if  this  could  be  shown,  it  is  evident  that  they 
must  have  shared  in  the  disturbance  which  accompanied  the  metamorphism 
of  the  Knoxville  beds  at  Mt.  Diablo  to  the  northwest  and  at  San  Luis 
Obispo  to  the  south. 

An  immense  area  of  serpentine  exists  to  the  southwest  of  the  New 
Idria  district,  only  an  edge  of  which  is  included  in  the  map.  In  this,  as 
in  some  other  respects,  there  is  a  close  analogy  between  New  Idria  and  the 
area  surrounding  the  Redington  mine.  Partially  serpentinized  rocks  are 
common,  and  the  descriptions  of  the  transitions  from  sandstone  to  serpen- 
tine given  in  the  chapter  on  the  Knoxville  district  would  apply  without 
change  to  occurrences  observed  in  this  district.  Professor  Whitney  here 
saw  masses  of  serpentine  consisting  of  radially  arranged  fibers  in  concentric- 
layers,  which  he  also  considered  as  showing  the  unquestionably  metamor- 
phic  origin  of  the  mineral. 

Shales  are  also  largely  represented  here  among  the  metamorphic  rocks, 
and  at  Venado  Peak  argillaceous  rocks  of  this  description  pass  over  by 
gradual  transitions  into  phthanites.  Some  of  the  shales  are  so  little  altered 
that  fossils  might  have  been  preserved  in  them,  but  prolonged  and  earnest 
search  failed  to  reveal  even  a  fragment  of  a  shell.  Similar  rocks  devoid  of 
fossils  are  provokingly  frequent  in  the  Coast  Ranges.  AuceUa  was  evidently 
a  gregarious  mollusk,  and  where  specimens  are  found  they  are  sometimes 
very  abundant;  but,  though  these  animals  lived  on  both  sandy  and  muddy 
bottoms,  the  localities  in  which  they  flourished  seem  to  have  been  few. 

The  metamorphic  rocks  have  been  dislocated  in  the  most  violent  man- 
ner; indeed,  the  greater  part  of  the  mass  was  crushed  at  the  time  of  the 
metamorphism  to  a  small  rubble.  This  is  the  case  throughout  the  entire 
quicksilver  belt  and  renders  it  utterly  impossible  to  plot  any  sections  of 
the  metamorphic  strata.  I  had  hoped,  by  taking  very  numerous  dips  in  the 
metamorphic  area,  to  determine  at  least  a  prevailing  system  in  the  strati- 
graphical  arrangement  of  the  mass,  for  such  a  system  might  very  well 
exist  in  spite  of  a  large  amount  of  comminution.  Hundreds  of  dips  were 
accordingly  measured  all  over  the  metamorphic  area,  but  without  any 
result.  No  fortuitous  distribution  of  directions  could  have  been  less  ac- 
cordant The  position  of  the  serpentine  belt,  however,  and  observations 


294  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

made  elsewhere  on  the  structure  of  the  Coast  Ranges,  lead  me  to  believe 
that  the  axis  of  upheaval  at  the  close  of  the  Neocomian  coincided  in  direc- 
tion with  the  present  range,  as  was  the  case  at  later  uplifts.  In  the  area 
mapped  the  various  classes  of  metamorphosed  rocks  are  so  mingled  that  it 
is  not  practicable,  as  at  Knoxville  and  New  Almaden,  to  lay  down  areas 
which  are  chiefly  serpentinoid. 

The  serpentine  near  the  county  line  contained  a  considerable  quantity 
of  chromic  iron,  which  is  said  to  have  been  mined  at  one  time  under  the 
belief  that  it  was  a  silver  ore.  The  workings  are  now  so  nearly  obliterated 
that  nothing  could  be  made  out  as  to  the  character  of  the  occurrence.  As 
is  pointed  out  in  Chapter  III,  particles  of  chromic  iron  are  very  common 
in  the  serpentine  of  the  Coast  Ranges. 

The  chico.-— Resting  against  the  metatnorphic  rocks  are  the  Chico  beds. 
These  are  thousands  of  feet  in  thickness  and  the  exposures  are  verv 
extensive,  but  the  rocks  are  very  poorly  supplied  with  fossils.  With  much 
trouble,  however,  a  small  collection  of  fossils  was  gathered,  and  among 
these  Dr.  White  recognized  Ammonites,  Baculitcs,  Iiiocerainus,  and  Lima 
These  genera  are  characteristic  and  the  identifications  are  sufficient  to 
establish  the  age  of  the  beds  beyond  a  doubt.  The  rocks  of  this  series  are 
for  the  most  part  soft,  coarse,  arcose  sandstones  of  a  reddish-gray  tint;  but 
small  quantities  of  shale,  conglomerate,  and  limestone  are  here  and  there 
intercalated  between  arenaceous  beds.  The  prevalent  rock  is  so  soft  that 
branches  of  manzanita  bushes,  growing  across  croppings  and  swayed  by 
winds,  sometimes  wear  channels  inches  deep  in  the  rock  without  being 
killed.  Near  the  mine,  however,  some  induration  has  taken  place,  and 
cinnabar  has  been  deposited  in  the  Chico  sandstone.  Seams  of  gypsum, 
sometimes  selenite,  are  common  enough  in  these  beds,  as  Avell  as  in  the 
Tejon  and  Miocene  strata.  There  are  also  at  many  points  dark  brownish- 
red,  spherical  concretions  in  this  sandstone  which  are  very  firm.  I  do  not 
doubt  that  the  induration  of  these  masses  has  been  effected  by  the  action 
of  some  substance  which  once  existed  at  or  near  the  centers.  One  of  the 
concretions  from  this  locality  was  found  to  contain  a  fossil  at  the  center, 
and  a  few  similar  occurrences  have  been  met  with  elsewhere.  In  Chapter 
III,  I  have  given  the  results  of  an  investigation  of  one  of  the  concretions 


UNCONFORMITY.  295 

containing-  no  fossil  from  the  New  Idria  Chico  beds,  which  seem  to  prove  that 
the  induration  is  due  to  the  decomposition  of  an  organic  nucleus. 

When  the  rock  is  of  nearly  uniform  texture  spherical  concretions  often 
extend  over  several  laminae,  the  regularity  ef  which  is  undisturbed  by  the 
induration  of  the  nodule.  In  other  cases  the  concretions  are  flattened,  and 
this  form  seems  to  be  related  to  the  unequal  composition  of  adjoining  beds. 
The  shales  of  this  formation  are  remarkable  for  nothing  but  their  rarity. 
Conglomerates  are  still  less  frequently  found,  but  such  a  bed  is  exposed  on 
the  road  from  the  furnaces  to  the  upper  mine  at  a  distance  of  a  few  hundred 
feet  from  the  contact  with  the  metamorphic  mass. 

Non-conformity. — This  is  an  occurrence  of  much  importance,  for  the  pebbles 
which  it  contains  are  metamorphic  and  are  composed  of  siliceous  and  ser- 
pentinoid  rocks.  Such  rocks  must  therefore  have  been  exposed  to  erosion 
at  the  time  when  the  lower  portion  of  the  Chico  was  deposited,  and  probably 
at  no  great  distance  from  the  position  now  occupied  by  the  conglomerate. 
There  is  no  reason  to  suppose  that  the  metamorphic  rocks  were  other  than 
those  now  exposed,  and  the  metamorphism  with  the  attendant  upheaval  must 
consequently  have  taken  pl&ce  prior  to  the  deposition  of  the  Chico,  or,  in 
other  words,  there  must  be  a  lack  of  conformity  between  the  two. 

Before  the  pebbles  of  this  conglomerate  had  been  studied  under  the 
microscope  I  had  made  out  the  existence  of  the  non-conformity  on  structural 
grounds,  as  was  described  in  Chapter  V.  It  is  unnecessary  to  repeat  that 
argument  at  length  here. 

The  Chico  beds  constitute  a  conformable  series,  inclined  at  an  angle 
which  is  high  close  to  the  contact  with  the  metamorphic  rocks  and  dimin- 
ishes as  one  proceeds  northward.  A  result  of  the  steepness  of  the  contact  is 
the  absence  of  any  single  exposure  by  which  a  non-conformity  can  be 
proved  beyond  a  doubt;  but  a  study  of  the  relations  along  the  whole  line 
leads  at  least  as  satisfactorily  to  the  conclusion  that  there  is  a  want  of  con- 
formity. Over  nearly  the  entire  area  mapped  the  Chico  strata  strike  along 
gently  undulating  lines  whose  minimum  radius  of  curvature  is  usually  about 
one  mile,  and  this  regularity  is  persistent  up  to  the  contact.  Only  at  the 
western  edge  of  the  map  is  there  considerable  disturbance  among  beds  of 
the  Chico  series. 


296 


QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 


The  line  of  contact,  on  the  other  hand,  is  marked  by  many  irregulari- 
ties. In  the  following  diagram  (Fig.  1 1)  the  line  a  b  is  the  contact  as  it  would 
appear  were  a  horizontal  plane  passing  through  it  at  the  mean  elevation  of 
3,800  feet.  The  line  c  d  shows  the  intersection  of  one  of  the  Chico  strata 
with  the  3,300-foot  level.  The  stratum  for  which  this  subterranean  contour 
line  was  deduced  was  followed  almost  continuously  for  the  entire  distance 
shown,  a  closely  adjacent  stratum  being  sometimes  substituted  for  a  short 
distance.  Other  strata  were  mapped  as  far  as  they  could  be  followed,  in 
several  cases  for  over  half  a  mile.  The  curvature  was  in  all  cases  similar  and 
the  conformity  was  absolute.  In  comparing  this  figure  with  the  geological 
map  it  is  of  course  to  be  remembered  that  the  contact  on  the  latter  is  laid 
down  as  it  appears  on  the  actual  surface,  while  in  the  figure  it  is  represented 
as  it  would  appear  were  the  country  a  horizontal  plane.  At  one  point  the 
line  of  the  figure  is  still  further  modified.  The  steep  hill  immediately  south 
of  the  Hacienda  or  Bell  tunnel  is  not  wholly  in  place.  A  large  landslide 
has  begun  here  and  an  immense  mass  of  metamorphic  material  has  moved 
northward  past  the  solid  contact.  For  this  movement  allowance  has  been 
made  in  drawing  the  figure. 


FIG.  11.  a  b,  contact  butween  metamorphic  rocks  and  Chico  beds  reduced  to    intersection  with  a  horizontal  plane  ;    c  d, 
strike  of  a  Chico  stratum  reduced  to  intersection  with  a  horizontal  plane. 

The  structure  is  evidently  consistent  with  a  non-conformity.  It  is  also 
conceivable  that  the  entire  mass  of  strata  was  laid  down  conformably  and 
that  the  disturbance  and  metamorphism  ceased  abruptly  at  the  line  repve- 


UNCONFORMITY.  297 

sented  by  the  contact.  In  that  case,  however,  still  greater  irregularities 
in  the  line  of  contact  would  almost  certainly  exist,  as  well  as  outlying 
patches  of  metamorphic  rock  and  transitions  between  metamorphosed  and 
unaltered  beds  along  the  contact.  The  presence  of  siliceous  and  serpentinoid 
pebbles  in  the  Chico  conglomerate  would  also  ba  very  mysterious.  The 
non-conformity  above  the  metamorphic  series  is  thus  substantially  certain 
from  the  observations  at  New  Una  alone.  Confirmatory  evidence  was  ob- 
tained on  the  north  fork  of  Cantua  Creek,  some  five  miles  southeast  of  New 
Idria.  At  that  locality  the  creek  cuts  through  hills  capped  with  heavy  beds 
of  Chico  sandstone,  which  are  inclined  at  an  angle  of  approximately  30° 
and  strike  at  right  angles  to  the  course  of  the  creek;  but  this  interval  is 
only  a  few  hundred  feet  in  width  and  there  can  hardly  be  a  doubt  that,  if 
the  talus  were  removed,  the  Chico  beds  would  be  found  resting  on  the  up- 
turned edges  of  the  metamorphic  rocks.  Had  the  thin-bedded  rocks  been 
driven  into  their  present  position  after  the  deposition  of  the  Chico  rocks, 
the  latter  could  not,  in  my  opinion,  have  been  so  little  disturbed.  The  beds 
are  not  visibly  flexed  and  form  cliffs  at  their  upper  end.  In  the  creek  the 
metamorphic,  thin-bedded  sandstones  are  exposed  in  a  nearly  vertical  posi- 
tion. The  interval  between  the  creek  bed  and  the  exposed  sandstones  is 
covered  by  detritus  and  vegetation. 

The  mine  affords  one  important  exposure  of  the  contact  below  the 
Chico.  This  is  in  the  Bell  tunnel,  tn\  position  and  course  of  which  are  shown 
on  the  map.  Its  mouth  is  in  the  Chico.  strata,  and  it  passes  far  into  the  meta- 
morphic mass.  Ths  rocks  near  the  entrance  are  thick  beds  of  soft,  tawny 
sandstones,  with  occasionally  thin  masses  of  shale.  They  are  unbroken  and 
dip  north  30°  east  at  angles  of  65°,  with  some  small  variations.  As  the 
contact  is  approached  breaks  begin  to  appear  in  the  sandstones,  due  to  spe- 
cial disturbances  in  the  region  of  the  mine,  which  will  be  referred  to  in  de- 
scribing the  deposit.  While  there  are  fractures  and  small  faults  along  this 
part  of  the  tunnel,  the  rock  nowhere  seems  to  be  flexed  and  the  beds  re- 
cover their  normal  position  at  frequent  intervals.  The  beds  are  neither  silici- 
fied  nor  serpentinized,  but,  as  at  the  surface,  there  are  occasional  stringers 
of  calcite  and  gypsum.  At  a  point  90  feet  northward  from  the  last  station 
before  the  main  cross-cut  is  reached,  or  at  a  distance  of  about  twenty- 


298  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

four  hundred  feet  from  the  mouth  of  the  tunnel,  a  change  takes  place. 
Instead  of  the  heavy  sandstone  beds  with  an  occasional  seam  of  shale,  the 
thin,  indurated  strata  so  prevalent  in  the  Knoxville  series  make  their  appear- 
ance. Instead  of  being  flat  like  the  sandstones  or  so  little  flexed  that  the 
curvature  i-s  insensible  in  the  width  of  the  tunnel,  these  thin-bedded  rocks 
are  almost  everywhere  greatly  contorted,  and  for  a  considerable  distance 
the  tunnel  is  driven  through  an  angle  of  flexure  so  sharp  that  the  strata 
coming  in  at  the  roof  in  one  direction  pass  out  at  the  floor  in  another,  dif- 
fering1 from  the  first  by  90°.  This  sudden  transition  from  uncoutorted  to 
closely  flexed  strata  and  from  soft  sandstones  to  siliceous,  thin-bedded 
rocks  certainly  suggests  a  non-conformity  most  forcibly.  Indeed  I  know 
of  no  other  theory  which  seems  adequate  to  explain  the  circumstances; 
but  along  the  actual  contact  motion  has  taken  place  and  in  regions  of  great 
disturbance  the  results  of  faulting  sometimes  closely  simulate  the  aspect  of 
non-conformity.  From  this  exposure  alone,  therefore,  I  should  be  unwill- 
ing to  pronounce  upon  the  structure. 

While  there  is  no  single  exposure  at  New  Idria  from  which  a  non-con- 
formity can  be  demonstrated,  there  are  many  which  are  most  satisfactorily 
explained  by  the  supposition  of  a  lack  of  conformity;  indeed,  when  once 
the  idea  of  a  break  in  the  continuity  of  sedimentation  is  suggested,  a  mere 
inspection  of  the  country  from  any  higher  points  affords  the  experienced 
geologist  strong  evidence  in  its  favor.  The  transition  from  the  crumpled, 
chaotic,  metamorphic  rocks  to  the  gently  undulating  sandstone  beds  is  too 
complete  and  too  abrupt  to  fit  easily  into  any  other  theory  of  structure. 

There  is  much  other  structural  evidence  in  the  Coast  Ranges,  both 
direct  and  indirect,  besides  that  obtained  at  New  Idria,  of  this  extremely 
important  non-conformity.  Its  existence  is  also  an  inevitable  concomitant 
of  the  time  relations  of  the  two  sets  of  strata  involved,  for  between  the 
period  of  the  Knoxville  beds  and  that  of  the  Chico  there  is  a  gap  of  hun- 
dreds of  thousands  of  years. 

It  would  have  been  nearly  impossible  to  work  out  the  extremely 
important  structural  geology  of  this  district  without  a  topographical  map  of 
great  accuracy.  The  map  prepared  for  this  report  by  Mr.  J.  D.  Hoffmann 
is  entirely  satisfactory  in  this  respect.  It  may  be  depended  upon  for  every 


THE  ECOENE.  299 

detail  and  would  bear  enlargement  to  three  times  the  scale  on  which  it  is 
published. 

Eocene. —  The  Tejon  formation  is  also  represented  at  New  Idria.  Fossils 
were  found  in  it  by  Mr.  Gabb,  and  my-party  also  collected  a  number  of 
characteristic  forms.  For  the  reasons  set  forth  in  Chapter  V  it  has  been 
for  many  years  a  mooted  point  whether  the  Tejon  series  formed  a  portion 
of  the  Cretaceous  or  of  the  Tertiary.  The  fact  is  that  it  may  be  said  to 
belong  to  both.  There  is  neither  fault  nor  unconformity  between  the 
Chico  and  the  Tejon  at  New  Idria;  the  deposition  of  sands  went  on  unin- 
terruptedly from  the  one  period  to  the  other,  and  Dr.  White  shows  that 
there  was  a  continuity  of  life  also  between  the  two.  In  short,  in  California 
there  is  no  sharp  distinction  between  the  two  series,  though  the  Chico- 
Tejon  beds  are  divisible  paleontologically  into  an  upper  and  a  lower  portion 
connected  by  transitions.  The  character  of  the  faunas,  however,  proves 
that  the  Chico  must  be  regarded  as  the  concluding  period  of  the  Creta- 
ceous era  and  the  Tejon  as  the  opening  period  of  the  Tertiary.  Such  a 
transition  has  been  observed  nowhere  else  in  America  or  in  Europe. 

Even  if  the  strata  at  New  Idria  were  more  abundantly  supplied  with 
fossils  than  they  are,  a  hard  and  fast  line  could  not  be  drawn  between  the 
Chico  and  Tejon.  The  demarkation  indicated  on  the  map,  however,  is  not 
wholly  arbitrary.  The  beds  containing  distinctly  Tejon  fossils  both  here 
and  at  Mt.  Diablo  differ  physically  from  the  Chico.  The  upper  series  is 
composed  almost  exclusively  of  sandstones  which  are  remarkably  light 
colored  —  often  pure  white  —  while  the  Chico  sandstones  are  firmer  and  of 
a  tawny  color,  These  characteristics  are  so  persistent  that  I  have  drawn 
the  outline  of  the  Tejon  at  the  lowest  of  the  white  beds.  The  included  area 
of  course  embraces  all  the  known  localities  at  which  fossils  referable  to 
the  upper  series  are  found. 

The  line  drawn  between  the  Chico  and  the  Tejon  is  rather  irregular 
on  the  map  and  at  its  easterly  end  bends  sharply  northward.  This  suggests 
a  non-conformity,  but  the  suggestion  is  misleading.  A  portion  of  the  irreg- 
ularity of  the  outline  is  due  to  the  unevenness  of  the  surface.  At  many 
exposures  the  beds  are  shown  in  perfect  conformity,  but  the  soft,  white 
beds  have  yielded  to  the  stress  accompanying  upheaval  more  than  the  great 


300  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

mass  of  the  Chico,  and  the  dip  is  in  some  places  reversed  near  the  contact, 
giving  this  line  greater  irregularity  than  it  would  possess  had  the  strata 
been  more  uniform  in  physical  character.  Towards  the  east  end  of  the 
contact  there  has  been  a  certain  amount  of  disturbance,  seemingly  pro- 
duced by  a  longitudinal  stress.  It  has  affected  both  series  of  beds,  and 
here  as  elsewhere  there  is  evidence  of  conformity.  Near  the  western  end 
of  the  contact  a  tongue  of  Chico  rock  is  shown  projecting  into  the  Tejon 
area.  This  tongue  is  superficially  composed  of  sandstone  rubble,  probably 
brought  down  from  the  more  elevated  area  by  floods.  There  is  no  reason 
to  doubt  that  the  contact  of  rock  in  place  follows  the  dotted  line  drawn  on 
the  map  across  this  tongue. 

Although  the  greater  part  of  the  Tejon  beds  are  nearly  white,  some  of 

them  contain  dark,  ferruginous  concretions  of  a  kind  similar  to  those  noted 

in  the  Chico.     These  nodules  are  less  abundant  and  less  regular  in  the 

•    Eocene.     In  passing  it  may  be  noted  that  Miocene  rocks  in  the  Vallecitos 

Canon  are  thickly  studded  with  spherical  concretions  of  the  same  kind. 

The  Tejon  is  the  coal-bearing  formation  at  Mt.  Diablo.     At  New  Idria 

also  there  is  a  coal  seam  near  the  San  Carlos  Creek,  just  north  of  the  limits 

of  the  map.     Fuel  was  supplied  to  the  mining  company  for  the  blacksmith- 

,.  shop  and  other  purposes  for  many  years  from  this  seam,  but  it  was  of  purely 

local  importance. 

The  thickness  of  the  Chico-Tejon  strata  is  very  great.  The  thickness 
of  the  least  disturbed  portion  represented  upon  the  map,  when  measured 
perpendicular  to  the  stratification,  is  about  seven  thousand  feet,  but  the 
entire  series  is  not  included  in  the  area  mapped.  There  cannot  be  less  than 
ten  thousand  feet  of  the  complete  series  How  such  enormous  accumula- 
tions, consisting  almost  exclusively  of  sandstone,  can  have  been  formed  is 
a  mystery.  There  are  great  thicknesses  of  Miocene  beds  also  within  a  few 
miles  of  New  Idria  on  both  sides  of  the  range,  and  these  too  are  substan- 
tially composed  of  sandstone. 

Absence  of  uvas. —  No  eruptive  rocks  are  known  to  exist  nearer  to  New 
Idria  than  about  ten  miles.  There  is  a  considerable  area  of  basalt  to  the 
northwest  of  Vallecitos  Canon,  or  to  the  southeast  of  the  Cerro  Bonito  mine. 
Pebbles  of  lava  are  also  to  be  found  along  the  lower  portion  of  San  Carlos 


NEW  IDEIA  MINES.  301 

Creek.  The  absence  of  eruptive  rocks  close  to  the  mines  of  New  Idria, 
however,  does  not  preclude  the  former  existence  of  hot  springs  here.  It 
simply  leaves  the  question  to  be  decided  by  analogy. 

General  description  of  the   New  Idria The    depOSltS    of    tll6     New    Idria    mine    ai'6 

substantially  inclosed  in  rocks  of  the  metamorphic  series.  Of  these,  ser- 
pentine is  represented  only  to  a  small  extent,  the  prevailing  rocks  being 
shales  and  sandstones  in  various  stages  of  alteration.  An  important  por- 
tion of  the  shales  have  been  converted  into  phthanites,  while  some  of  the 
sandstone  has  almost  escaped  induration.  The  deposits  are  near  the  con- 
tact between  the  metamorpliic  rocks  and  the  adjoining  Chico  sandstones; 
so  also  is  the  San  Carlos  mine  to  the  east.  At  a  distance  of  about  three 
thousand  feet  westward  from  the  New  Idria,  however,  the  limiting  line  of 
the  me  tarn  orphic  area  bends  in  a  southerly  direction,  and  in  the  bay  thus 
formed  is  a  mass  of  somewhat  indurated  Chico  sandstone,  in  which  cinna- 
bar has  been  found.  This  occurrence,  known  as  the  Washington  crop- 
pings,  shows  at  least  that  the  period  of  ore  deposition  is  later  than  the 
Chico,  or  that  it  is  Post-Cretaceous. 

The  New  Idria  mine  has  disclosed  important  deposits  of  three  distinct 
types:  reticulated  masses,  or  stockvvorks,  impregnations,  and  true  fissure 
veins  —  in  short,  all  the  principal  classes  of  original  ore  deposits  are  rep- 
resented. There  is  no  question  whatever  as  to  the  fact  of  a  connection  be- 
tween these  deposits  and  a  system  of  fissures,  but  this  system  is  unusually 
complex  in  some  particulars  which  are  of  the  greatest  importance  in  rela- 
tion to  the  economic  value  of  the  property.  A  portion  only  of  the  deposits 
was  accessible  at  the  time  of  my  visit. 

The  upper  part  of  the  deposits,  and  particularly  the  northeastern  por- 
tion, consisted  of  irregular  stockworks.  Only  the  excavations  close  to  the 
croppings  are  now  accessible.  They  show  siliceous  shales  and  phthanites, 
containing  a  few  carbonized  plant  remains,  with  small  seams  and  "paints" 
of  cinnabar.  The  ore,  accompanied  by  pyrite  and  quartz,  has  sometimes 
filled  cracks  across  metamorphic  strata  and  has  frequently  also  followed 
the  bedding  exactly  as  it  is  observed  in  innumerable  mines  and  prospects 
throughout  the  Coast  Ranges.  There  is  nowhere  in  these  dense  rocks  any 
indication  of  impregnation.  The  descriptions  of  the  great  ore  bodies  of  the 


302  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

northeast  part  of  the  upper  mine  by  Mr.  J.  W.  C.  Maxwell,  who  was  for 
many  years  superintendent,  and  the  account  published  by  Professor  Whit- 
ney show  that  these  ore  bodies  also  consisted  essentially  of  broken  rock 
the  interstitial  spaces  of  which  had  been  filled  in  with  ore.  The  various 
bonanzas  showed  little  evidence  of  systematic  arrangement,  though  they 
were  often  connected  by  stringers  or  "hilos"  of  ore;  but  the  plan  of  the 
workings  proves  that  the  prevailing  strike  was  northeast  and  southwest. 
There  are  two  well  marked  veins  in  this  mine  One  of  them,  the  New 
Hope  lode,  was  enormously  rich  and  was  very  remarkable  for  the  fact  that 
the  ore  was  mainly  composed  of  metacinnabarite  with  which  a  little  cinna- 
bar was  mingled.  This  vein  is  in  the  eastern  portion  of  the  ore-bearing 
ground.  It  strikes  approximately  northwest  and  southeast.  The  other  vein 
is  at  the  southwestern  portion  of  the  ore-bearing  ground  and  is  known  as 
the  Elvan  Streak  vein.  This  is  a  misnomer,  for  elvan  is  quartz  prophyry, 
while  at  New  Idria  neither  this  nor  any  other  eruptive  rock  occurs.  The 
Elvan  Streak  is  for  long  distances  a  clean-cut  fissure,  filled  with  decom- 
posed attrition  products  which  are  impregnated  with  cinnabar.  In  contact 
with  the  vein  are  ore  bodies,  in  part  stockworks  and  in  part  impregnations. 
This  vein  strikes  in  about  the  same  direction  as  the  New  Hope,  and  near  it 
at  one  point  were  found  some  tons  of  metacinnabarite.  To  the  southeast 
it  is  cut  out  by  a  clay  seam.  Ore-bearing  ground  has  also  been  developed 
by  the  Bell  tunnel,  the  deposit  consisting  of  a  very  large  but  low  grade 
impregnation  of  cinnabar  in  sandstone. 

Disposition  of  the  ore  bodies — The  disposition  and  form  of  the  deposits  as  indi- 
cated by  the  above  notes  are  sufficiently  intricate,  but  the  structure  of  the 
country  is  still  further  complicated  by  the  presence  of  a  clay  wall  running 
diagonally  across  the  ore-bearing  ground  near  the  eastern  end  \and  divid- 
ing the  New  Hope  vein  from  the  remainder  of  the  principal  deposits.  The 
presence  of  this  wall  renders  plausible  each  of  two  distinct  theories  as  to 
the  fissure  system  of  the  mine,  but  leaves  neither  free  from  doubt. 

The  plan  of  the  workings  is  so  complex  as  to  be  very  difficult  to  fo-1-  ' 
low  and  the  records  of  the  mine  contain  no  vertical  section  of  the  ground. 
Cross-sections  were  perhaps  unnecessary  to  those  thoroughly  familiar  with 
the  workings,  but  it  is  impossible  for  others  to  obtain  an  accurate  idea  of  the 


NEW  IDRIA  MINE. 


303 


form  of  the  stockworks  from  the  mere  projection  on  a  horizontal  plane. 
No  purpose  would  therefore  be  answered  by  reproducing  the  plan  of  the 
mine  in  this  volume,  but  an  idea  of  the  distribution  of  the  deposits  will  be 
conveyed  by  the  following  sketch,  in  which  some  of  the  ore  bodies  and  the 
position  of  the  clay  wall  are  shown  in  horizontal  projection  in  a  somewhat 
generalized  manner  (Fig.  12).  Leaving  the  New  .Hope  out  of  consider- 


FIG.  12.  es,  Elvan  Streak,     n  ft,  Now  Hope.     Id,  Stockworks.      6,  Bell  tunnel  ore  chamber.    //,  Strike  of  clay  wall 
dividing  the  New  Hope  from  the  remaining  ore  bodies. 

ation  for  a  moment,  it  is  evident  that  the  remaining  deposits  may  be  divided 
into  two  groups,  one  including  the  Elvan  Streak  and  contiguous  bonanzas, 
together  with  the  Bell  tunnel  ore  body,  while  the  other  cluster  comprises 
the  stockworks.  The  former  of  these  groups  I  have  had  good  opportuni- 
ties of  examining.  It  is  beyond  question  that  north  of  the  clay  wall  the 
Klvan  Streak  is  a  fairly  regular,  nearly  vertical  vein,  which  has  afforded  a 
passage  for  ore-bearing  solutions.  These  have  permeated  the  walls  wher- 
ever they  were  permeable  and  ore  chambers  have  been  formed  as  adjuncts 
to  the  vein.  The  Bell  tunnel  body  consists  of  very  slightly  moditied  sand- 
stone of  porous  texture,  impregnated  with  cinnabar,  which  also  forms  seams 
wherever  cracks  in  the  rocks  permitted  such  deposition.  It  lies  in  the  di- 
rection of  the  strike  of  the  Elvan  Streak,  and  the  fissures  through  which 
the  two  were  charged  with  ore  must,  I  think,  be  very  closely  related. 


304  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

They  may  be  identical;  but,  if  not,  they  are  probably  parallel,  associated 
fissures.  The  developments  accessible  to  me  were  insufficient  to  determine 
tins  point.1 

With  reference  to  the  stockworks,  my  information  is  obtained  at  second 
hand  and  is  very  imperfect,  I  hesitate,  therefore,  to  express  decided  opinions 
about  them.  It  is  noteworthy,  however,  that  the  most  westerly  of  these 
deposits,  the  Florencio  Diaz,  is  approximately  parallel  to  the  Elvan  Streak, 
as  is  also  the  New  Hope,  to  which  further  reference  will  bo  made  below. 
Most  of  the  other  stockworks  have  a  strike  nearly  perpendicular  to  the 
Elvan  Streak.  The  clay  wall  makes  an  angle  of  about  45°  with  each  of 
these  directions. 

The  fissure  system.— The  most  momentous  question  concerning  the  structure 
of  this  mine  is  the  position  of  the  principal  fissures,  those,  namely,  through 
which  the  ore-bearing  solutions  found  access  to  the  productive  ground;  for 
upon  this  question  depends  the  plan  to  be  adopted  in  developing  the  prop- 
erty. The  main  fissures  almost  certainly  coincide  in  direction  with  one  or 
other  of  the  lines  discussed  above ;  indeed,  it  may  be  assumed  with  some 
confidence  that  either  the  clay  wall  or  the  Elvan  Streak  lies  on  the  princi- 
pal fissure  or  on  one  of  a  system  of  parallel  fissures  of  nearly  equal  im- 
portance. The  existence  of  the  stockworks  is  susceptible  of  explanation  as 
a  subordinate  structural  phenomenon.  The  theory  which  was  adopted  in 
developing  the  mine  is  that  the  clay  is  the  hanging  wall  of  the  ore-bearing 
ground.  The  Elyan  Streak  then  represents  a  cross-course  and  the  New 
Hope  is  an  isolated  deposit  in  the  hanging  wall.  Great  weight  is  to  be 
given  to  this  opinion,  which  was  formed  by  the  daily  study  of  the  exposures. 
It  is  evidently  possible,  however,  that  the  main  fissures  may  coincide  in 
direction  with  the  Elvan  Streak  and  the  New  Hope  and  that  the  clay  wall 
may  represent  a  cross-course  or  a  fault.  I  confess  myself  strongly  inclined 
to  this  latter  view. 

Had  the  fault,  fissure  been  the  channel  of  the  ore  solutions,  one  would 
expect  to  find  the  chief  ore  bodies  in  contiguity  to  it  and  coinciding  with 
it  in  general  direction.  It  is  a  common  thing  to  find  deposits  of  very 

1  Early  in  1887  ore  was  struck  in  the  Bell  tunnel  workings  which  resembled  that  of  the  Elvau 
Streak.    This  tends  to  confirm  the  above  hypothecs. 


NEW  IDEIA  MINE.  305 

irregular  outlines  and  with  ramifications  extending  into  the  walls  along  the 
fissures  to  which  they  owe  their  origin  ;  but  such  deposits  almost  invariably 
follow  the  fissure  to  a  certain  extent  and  present  a  large  contact  surface 
with  it,  No  better  illustration  of  this  usual  relation  could  be  given  than 
the  Elvan  Streak,  with  its  accompanying  bonanzas.  Nothing  of  the  kind 
is  apparent  at  the  fault  fissure.  Where  ore  touches  it  at  all,  the  surface 
common  to  both  is  small.  'As  a  rule  the  fissure  containing  this  clay  seam 
carries  no  ore  whatever,  while,  had  it  been  the  channel  of  the  ore-bearing 
solutions,  one  would  expect  to  find  at  least  small  quantities  of  cinnabar 
nearly  everywhere  in  it,  as  is  actually  the  case  in  the  Elvan  Streak.  It  is 
very  true  that,  in  wide  veins  bounded  by  selvages  of  clay,  the  clay  is  often 
barren;  but  such  cases  are  not  comparable  with  the  ore-bearing  ground  of 
the  New  Idria  as  a  whole.  The  prevailing  character  and  disposition  of  the 
rock,  together  with  the  absence  of  a  defined  foot-wall,-  show  that  the  stock- 
works  are  not  comparable  to  pockets  in  a  vein,  but  to  chambers  adjacent 
to  a  vein  and  impregnated  from  it.  They  are  not  included  in  a  fissure,  but 
were  charged  with  oro  from  a  fissure.  The  stockworks  stand  to  some  fis- 
sures in  relations  similar  to  those  which  subsist  between  the  Elvan  Streak 
and  the  irregular,  contiguous  ore  bodies,  and  do  not  correspond  to  bunches 
of  cinnabar  between  the  walls  of  the  Elvan  Streak.  The  term  "  pipe  vein" 
is  used  by  von  Gotta  to  describe  some  deposits  analogous  to  these  ;  but  this 
expression,  having  been  employed  in  different  senses,  is  now  objectionable. 
A  corresponding  term  is  much  needed  to  describe  these  adjuncts  to  fissures. 
If  the  principal  fissure  of  this  mine  be  that  at  the  clay  wall,  the  clay, 
in  my  opinion,  fills  the  fissure.  In  that  case  the  absence  of  cinnabar  in 
considerable  quantity  from  this  clay  is  very  strange,  and  would  be  so  even 
if  the  Elvan  Streak  and  the  New  Hope  did  not  exist.  The  fissures  carry- 
ing these  two  veins,  however,  were  most  assuredly  in  existence  at  the  time 
of  ore  deposition,  showing  that  the  physical  character  of  the  rock  was  not 
such  as  to  preclude  deposition  in  fissures.  This  makes  tlie  absence  of 
ore  from  the  clay  wall  inexplicable  if  it  lies  on  the  main  fissure.  On  the 
other  hand,  if  the  clay  marks  the  position  of  a  fault  which  took  place  later 
than  the  deposition  of  ore,  its  own  character  and  the  relation  which  it  bears 
to  the  deposits  are  exactly  such  as  would  be  expected. 

MON  XIII 20 


306  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  clay  wall,  then,  appears  to  me  to  mark  a  fault  which  has  dislocated 
the  ore-bearing  ground.  This  fault  has  certainly  not  passed  by  the  deposits, 
for  it  has  cut  off  the  New  Hope  lode  from  the  other  ore  bodies.  The  hang- 
ing side  of  this  clay  wall  has  been  little  explored.  I  consider  it  the  most 
hopeful  portion  of  the  property  and  believe  that  explorations  should  be 
made  in  it.  I  have  no  data  tending  to  show  the  amount  of  the  fault  or  even 
its  direction  ,  but,  according  to  the  general  rule,  ore  bodies,  if  they  exist  and 
were  once  continuous  with  the  stockworks,  will  be  found  at  lower  levels  on 
the  hanging  side  of  the  fault.  The  El  van  Streak  and  the  New  Hope  appear 
to  me  to  mark  the  direction  of  the  main  fissures  of  the  mine.  The  disturb- 
ances which  made  room  for  the  stockworks  were  probably  contemporaneous 
with  those  which  produced  these  veins.  There  is  no  evidence  of  a  lapse  of 
time  between  them  and  it  is  not  difficult  to  understand  how  the  two  sets  of 
ruptures  may  have  been  brought  about  simultaneously.  Where  a  fracture 
is  accompanied  by  torsion,  two  sets  of  fissures  form  at  a  large  angle  to  each 
other.  This  has  been  demonstrated  experimentally  by  Mr.  Daubre'e.  The 
Coast  Ranges  are  full  of  evidences  of  torsional  fractures.  At  New  Idria 
and  elsewhere  highly  indurated  shales  are  very  common,  which,  even  in 
small  fragments,  exhibit  innumerable  cracks,  often  filled  with  quartz, 
which  are  divisible  into  two  systems  nearly  at  right  angles  to  each  other. 
There  is  plenty  of  evidence,  too,  that  fractures  like  those  produced  on  a 
small  scale  are  formed  also  on  a  large  one.  When  a  mass  is  broken  under 
a  torsional  stress,  the  force  will  not  in  general  be  equally  resolved  in  two 
directions  perpendicular  to  each  other  and  the  intensity  of  the  disturbance 
will  be  greater  on  one  set  of  ruptures  than  on  the  other.  The  more  violent  a 
rupture  in  the  rocks  is,  other  things  being  equal,  the  cleaner  will  be  the  fis- 
sures produced,  just  as  a  rifle-bullet  makes  a  round  hole  in  a  pane  of  glass, 
while  a  body  moving  at  a  low  velocity  crushes  the  whole  pane  to  fragments. 
The  ill  defined  zones  of  broken  rock  which  led  to  the  formation  of  stock- 
works  resulted  from  disturbances  less  violent  than  those  which  produced 
the  vein  fissures ;  but  the  two  sets  of  ruptures,  in  my  opinion,  were  due 
to  one  cause,  a  torsional  stress,  and  were  produced  at  the  same  time.  In 
searching  for  ore  these  vein  fissures,  and  perhaps  others  parallel  to  them, 
should  serve  as  guides.  Other  stockworks  may  very  likely  be  found  and 


AGE  OF  THE  NEW  IDRIA  ORE.  307 

the  connection  between  them  and  the  fissures  striking  northwest-southeast 
may  sometimes  be  indirect,  but  is  not  likely  to  be  entirely  wanting.  I  can 
see  no  indication  that  the  mine  is  exhausted,  and  I  believe  that  more 
bonanzas  exist  to  the  south  of  the  clay  \\all  and  perhaps  also  beneath  the 
old  group  of  stockworks,  or  on  the  lower  portion  of  the  Elvan  Streak  vein. 

Age  of  the  deposit. — The  existence  of  cinnabar  in  the  Washington  croppings 
shows  that  the  deposit  is  as  late  as  the  beginning  of  the  Tertiary  period. 
The  deposit  also  seems  to  be  later  than  the  tilting  of  the  Chico  beds, 
which  undoubtedly  took  place  at  the  uplift  shown  by  Professor  Whitney  to 
have  occurred  at  the  close  of  the  Miocene.  The  eruption  of  lavas  in  the 
Coast  Ranges  seems  to  have  begun  early  in  the  Pliocene,  probably  at  its 
commencement.  The  period  of  ore  deposition  at  New  Idria  thus  seems  to 
be  within  the  volcanic  epoch.  It  is  probably  much  more  recent  than  the 
Post-Miocene  upheaval.  The  quantity  of  cinnabar  found  in  the  soil  was 
small,  tending  to  prove  that  no  great  erosion  had  taken  place  since  its  depo- 
sition. The  ore  bodies  near  the  croppings  are  such  as  occur  most  frequently 
near  the  surface  as  it  existed  at  the  time  of  ore  deposition.  This  relation 
will  be  found  enlarged  upon  in  several  of  the  investigations  recorded  in  this 
volume,  particularly  that  of  the  Redington  mine,  where  also  stockworks 
and  veins  are  associated.  There  is  nothing  at  New  Idria  to  suggest  a  con- 
siderably greater  age  than  that  of  the  Redington  deposit.  The  latter  is  cer- 
tainly Post-Plio.ce.ne. 

In  a  drift  near  the  stockworks  on  the  lower  tunnel  level  I  met  with 
what  is  at  least  a  very  curious  and  suggestive  occurrence,  which  may  have  a 
bearing  on  the  age  of  the  deposit.  The  drift  had  not  been  used  for  years,  and 
the  walls  were  coated  with  epsorn  salts  and  other  secondary  minerals  to  the 
depth  of  nearly  two  inches.  In  this  loose  coating  I  found  a  tiny  seam  of 
cinnabar  which  had  quite  beyond  question  formed  in  this  position  since 
the  drift  had  been  abandoned.  This  proves  that  mercuric  sulphide  still 
exists  in  solution  in  the  waters  of  the  mine.  It  may  be  that  the  solution 
from  which  this  little  vein  was  deposited  was  a  remnant  of  that  from  which 
the  great  ore  bodies  were  precipitated.  If  so,  the  period  of  ore  deposition 
is  not  even  yet  wholly  past.  But  it  is  also  not  impossible  that  this  cinna- 
bar was  leached  from  the  stockworks  by  surface  waters  impregnated  with 


308  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sodium  sulphide,  this  reagent  resulting  from  the  reduction  of  soluble  sulphates 
by  timber  in  the  old  workings.  However  this  may  be,  the  occurrence  has 
a  bearing  upon  the  rarity  of  metacinnabarite  in  quicksilver  mines,  as  will 
be  shown  in  a  subsequent  chapter.  Any  solution  capable  of  dissolving 
mercuric  sulphide  will  tend  to  convert  metacinnabarite  into  the  red  ore. 

origin  of  the  deposits. —  Had  the  New  Idriii  mine  alone  been  examined  noth- 
ing could  be  affirmed  concerning  its  origin  further  than  that  the  ore  was 
deposited  from  solutions  which  obtained  access  to  the  mine  through  a  sys- 
tem of  fissures.  There  is  a  sulphur  spring  in  the  district,  but  it  is  cold  and 
may  have  nothing  to  do  with  volcanism.  It  is  certain,  however,  that  many 
deposits  in  California,  similar  in  all  essential  respects  to  that  of  New  Idria, 
have  been  precipitated  from  hot,  fluid,  volcanic  emanations.  It  is  also 
known  that,  in  some  cases,  very  hot  sulphurous  waters  which  rise  at  a 
distance  of  several  miles  from  any  known  lava  have  deposited  cinnabar. 
There  is  thus  much  reason  to  suppose  that  the  New  Idria  deposits  were 
formed  by  hot  volcanic  solutions,  and  no  reason  with  which  I  am  acquainted 
for  suspecting  any  other  origin. 

Combustible  gases  escaped  from  the  rock  in  great  quantities  during 
the  running  of  the  Bell  tunnel  and  produced  a  disastrous  explosion.1  This 
gas  was  probably  marsh  gas,  and  it  may  or  may  not  have  been  generated 
by  volcanic  action.  In  the  yEtna  mine  also,  the  ore  of  which  was  cer- 
tainly deposited  from  volcanic  springs,  as  well  as  at  Sulphur  Bank,  marsh 
gas  escapes. 

other  cinnabar  deposits. —  Besides  the  New  Idria  other  less  important  deposits 
of  cinnabar  have  been  found  within  the  limits  of  the  map,  though  none  of 
them  was  worked  during  my  visit.  The  San  Carlos  mine,  near  the  sum- 
mit of  San  Carlos  Peak,  is  in  the  rocks  of  the  metamorphic  series,  consist- 
ing of  thin,  indurated  shales,  which  have  been  whitened  either  by  solfataric 
action  or  by  leaching  consequent  upon  the  decomposition  of  pyrite.  No 
exposures  of  special  interest  were  accessible.  The  ore  is  said  to  have  been 

'  After  this  explosion  Mr.  Maxwell  employed  a  very  ingenious  mothod  of  lighting  the  tunnel  with- 
out the  use  of  fire.  A  mirror  was  placed  at  the  mouth  of  the  tunnel  and  was  kept  at  such  an  angle  as 
to  reflect  the  sun's  rays  into  it.  This  illumination,  which  was  repeated  for  my  benefit,  was  very  satis- 
factory. The  cloudless  sky  of  California  makes  this  method  entirely  practicable.  A  locomotive  head- 
light might  perhaps  be  used  to  advantage  in  a  .similar  manner  underground  in  certain  cases.  Possibly 
this  device  has  been  employed  before,  though  I  am  not  aware  of  it.' 


DEPOSITS  NEAR  NEW  IDRIA.  309 

rich,  and  a  considerable  quantity  was  extracted  and  delivered  at  the  New 
Idria  furnaces.  The  deposits  were  very  irregular  and  no  considerable  at- 
tempt seems  to  have  been  made  to  develop  the  property  in  depth.  The 
Aurora  or  Morning  Star  mine,  to  the  west  of  the  San  Carlos,  also  yielded  ore. 
Beyond  the  fact  that  excavations  were  made  here  nothing  is  visible.  Near 
the  falls  on  San  Carlos  Creek,  in  a  line  connecting  the  New  Idria  and  the 
Morning  Star,  a  little  cinnabar  is  said  to  have  been  found,  and  traces  of  ore 
have  been  detected  at  other  points,  all  of  which,  except  the  Washington  crop- 
pings,  are  within  the  metamorphic  area. 

Within  a  few  miles  of  the  area  mapped  and  to  the  southwest,  several 
mines  have  been  opened  and  again  abandoned.  The  Picacho  is  in  the  usual 
contorted,  highly  indurated  rocks,  partly  silicified  and  partly  converted  into 
carbonates.  The  ore  appeared  to  have  occurred  in  cracks  across  the  strata 
and  along  the  partings.1  It  is  said  that  the  first  continuous  quicksilver  fur- 
nace ever  built  in  the  State  was  erected  here  by  Mr.  John  Roach.  This 
structure  was  still  in  place  at  the  time  of  my  visit,  in  1884,  and  substantially 
in  the  same  condition  as  when  it  was  examined  by  Mr.  Goodyear  thirteen 
years  earlier.  Several  pounds  of  quicksilver  still  remained  in  the  wooden 
condenser,  showing  how  slowly  quicksilver  must  volatilize,  even  at  the 
high  temperatures  which  prevail  in  this  region  during  the  summer.  Near 
Clear  Creek  also  are  two  mines,  or  prospects,  at  which  ore  associated  with 
rocks  of  the  same  type  as  at  the  Picacho  was  extracted. 

1  In  a  prospectus  of  the  company  an  assay  is  given  according  to  which,  besides  mercury,  the  ore 
contains  considerable  amounts  of  both  gold  and  silver.  I  did  not  have  an  opportunity  of  verifying 
this  statement,  which  is  not  intrinsically  improbable. 


CHAPTER  X. 

DESCRIPTIVE  GEOLOGY  OF  NEW  ALMADEN  DISTRICT. 

[Atlas  Sheets  VII-XIII.] 

character  of  the  district — The  New  Almaden,  Enriqiuta,  and  Guadalupe 
mines  lie  nearly  south  of  San  Jost',  in  a  very  attractive  portion  of  the 
country.  The  fertile  valley  of  Santa  Clara  is  in  full  view  from  many  parts 
of  the  region  mapped,  and  the  Santa  Cruz  Range,  on  the  flanks  of  which 
the  deposits  occur,  is  picturesque.  Forests,  gorges,  and  brooks  diversify 
the  scenery,  the  character  of  which  reminds  one  of  portions  of  the  Sierra 
Nevada  rather  than  of  the  Coast  Ranges.  This  district  has  been  much 
more  productive  in  quicksilver  than  any  other  in  North  America,  and  since 
1850  it  has  yielded  about  four-fifths  as  much  metal  as  the  Almaden  of  Spain. 
The  general  geology  of -the  district  presents  oriS* special  feature  of  interest 
in  the  occurrence  of  rhyolite,  a  lava  not  yet  recognized  at  any  other  point 
in  the  Coast  Ranges.  Otherwise  the  general  geology  presents  no  novelty. 
The  great  opportunity  which  the  district  offers  is  for  the  study  of  structure 
disclosed  by  the  very  extensive  workings  of  the  New  Almaden  mine,  which 
are  said  to  measure  40  miles  in  length. 

Meismorphic  rocks. — The  greater  part  of  the  surface  is  occupied  by  rocks 
of  the  metamorphic  series.  The  age  of  these  rocks  is  known,  for  Mr. 
Gabb  found  near  the  mines  specimens  of  Aucc.Ua.  lie  does  not,  indeed, 
describe  the  rock  in  which  this  characteristic  shell  was  found,  nor  does  he 
give  the  exact  locality,  but  from  the  various  other  occurrences  mentioned 
in  this  volume  it  is  abundantly  proved  that  the  metamorphism  was  of  later 
date  than  the  period  at  which  Ancclla  flourished.  The  metamorphic  rocks 

310 


ROCKS  AT  NEW  ALMADEN.  311 

of  the  district  must  therefore  include  beds  containing  this  fossil  and  dating 
from  the  Neocomian.  I  did  not  succeed  in  finding  Amelia. 

The  metamorphic  rocks  are  for  the  most  part  identical  with  those  so 
prevalent  in  the  Coast  Ranges.  Pseudodiabase,  pseudodiorite,  phthanites, 
serpentine,  and  less  altered  rocks  are  abundant.  There  are  also  masses  of 
limestone,  one  of  which  is  quarried  for  the  manufacture  of  quicklime. 
The  occurrence  of  this  rock,  which  is  rather  rare  in  the  Coast  Ranges, 
affords  the  observer  an  opportunity  of  estimating  the  intensity  of  the  dis- 
turbance which  attended  the  metamorphism.  The  mass  of  limestone  from 
which  the  material  for  the  limekiln  is  obtained  must  have  formed  a  portion 
of  a  continuous  stratum,  but  this  has  been  so  broken  and  dislocated  that 
it  now  appears  only  as  irregular  patches  scattered  through  the  hills  and 
it  is  quite  impossible  to  restore  the  original  configuration  or  to  obtain  from 
it  any  aid  in  elucidating  the  stratigraphy  of  the  accompanying  rocks.  It 
was  found  possible  to  lay  down  the  serpentinoid  areas  in  this  district,  and 
they  have  received  a  separate  color  on  the  map.  As  on  the  other  maps 
where  this  has  been  done,  it  must  be  understood  that  no  sharp  division 
really  exists  and  that  the  purpose  of  the  delineation  is  simply  to  indicate 
as  nearly  as  may  be  the  distribution  of  a  certain  phase  of  metamorphism. 
The  general  structure  of  the  ridges  of  metamorphic  rock  seems  to  be  syn- 
clinal, as  it  is  at  so  many  points  in  the  Coast  Ranges. 

Granite. —  There  is  no  reason  to  doubt  that  granite  underlies  the  region 
of  New  Almaden,  though  at  a  considerable  depth.  In  the  Gavilan  Range 
and  at  Monterey,  to  the  south,  granite  is  exposedx  and  it  appears  also  to 
the  north,  near  Point  San  Pedro.  The  composition  of  the  sandstones  also 
indicates  that  the  material  of  which  they  are  composed  is  of  granitic  origin. 
As  is  shown  in  other  portions  of  this  report,  there  is  evidence  that  the  en- 
tire area  of  the  Coast  Ranges  is  underlain  by  granite,  and  the  facts  observed 
lead  almost  inevitably  to  the  conclusion  that  the  brush-covered  hills,  if 
examined  with  sufficient  care,  would  show  many  outcrops  of  the  rock 
which  have  hitherto  escaped  observation.  It  is  far  from  improbable  that 
granite  is  exposed  in  the  somewhat  inaccessible  country  southeast  of  New 
Almaden. 


312  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE, 


o.  —  At  various  points  in  the  district  thoroughly  rounded 
pebbles  of  a  peculiar,  coarse-grained,  crystalline,  gray  rock  ot  unusual 
hardness  were  found,  which  differ  strikingly  troni  any  rock  seen  in  place. 
They  must  have  come  from  the  higher  mountains  of  the  range  to  the  south- 
east, but  the  cropping^  were  not  identified.  This  rock,  when  examined 
under  the  microscope,  proved  to  be  an  olivinitic  gabbro,  the  only  rock  of 
the  kind  known  in  the  Coast  Ranges  and  the  only  rock  carrying  even  a 
trace  of  olivine  detected  during  this  investigation,  excepting  the  lavas. 
The  coarse  grain"  and  the  general  aspect  of  this  gabbro  suggest  for  it  a  very 
considerable  age,  but  the  olivines  are  very  fresh  and  show  only  thin  seams 
of  serpentine  along  the  cracks.  Whether  the  rock  is  eruptive  or  metamor- 
pliic  could  not  be  determined  from  the  material  available.  Olivine  does 
not  form  a  large  proportion  of  the  mass  and  decomposition  would  not  yield 
a  material  to  which  the  name  of  serpentine  would  apply  unless  other  con- 
stituents besides  olivine  were  serpentinized.  As  for  the  serpentine  of  the 
New  Almaden  area,  the  researches  recorded  in  Chapter  III  show  that  they 
are  derivative  of  sandstone,  as  is  the  case  in  all  the  districts  examined. 

Miocene.  —  Upon  the  metamorpliic  rocks  lie  some  areas  of  Miocene  sand- 
stones. These  are  soft,  yellowish  strata,  containing  a  considerable  number 
of  poorly  preserved  fossils  (Pecten,  Ostrea,  Balanus),  which,  however,  taken 
in  connection  with  structural  and  lithological  characteristics,  are  amply 
sufficient  to  fix  the  age  of  the  beds.  The  Miocene  rocks  are  considerably 
disturbed,  though  far  less  so  than  the  metamorpliic  series.  The  structural 
relations  indicate  a  non-conformity  between  the  Tertiary  and  the  metamor- 
pliic series,  which  is  also  demonstrated  by  the  presence  of  fragments  of  the 
earlier  strata  in  the  Miocene  beds.  Professor  Whitney  observed  sections 
exhibiting  this  non-conformity  within  a  few  miles  of  New  Almaden.  As  is 
shown  in  Chapter  V,  the  non-conformity  displayed  in  an  unequivocal  man- 
ner here  and  elsewhere  in  the  neighborhood,  as  well  as  in  the  San  Benito 
Valley,  is  really  between  the  Knoxville  series  and  the  Chico,  or  between 
the  Neocomian  and  the  Upper  Cretaceous.  Any  upheaval  between  the 
Neocomian  and  the  beginning  of  the  Miocene  would  produce  the  relations 
existing  at  Almaden.  But  at  New  Idria  and  elsewhere  the  Chico  and  the 
Tejon  are  conformable,  and  in  the  Vallecitos  Valley  and  at  Mt.  Diablo  the 


EHYOLITE. 

Tejon  and  the  Miocene  are  conformable.  Hence  there  is  no  room  for  an  ex- 
tensive and  violent  disturbance  of  this  region  between  the  beginning  of  the 
Chico  and  the  close  of  the  Miocene,  and  the  convulsions  attending  the  met- 
amorpliism  of  the  Neocomian  beds  must  have  preceded  the  Chico.  The 
period  is  still  more  closely  determined  by  the  discovery  of  the  Wallala 
beds,  which  are  much  earlier  than  the  Chico  and  are  referred  by  Dr.  White 
to  the  Middle  Cretaceous.  These  beds,  described  in  Chapter  V,  also  contain 
metamorphic  pebbles  and  show  that  the  metamorphism  and  upheaval  which 
accompanied  it  occurred  soon  after  the  close  of  the  Knoxville  period. 

Not  all  the  areas  laid  down  as  Miocene  on  the  map  are  fossiliferous, 
but  the  similarity  in  lithological  character  and  in  the  disturbance  which 
they  exhibit  is  sufficient  to  justify  their  reference  to  the  same  series.  The 
Miocene  beds  were  raised  and  folded  at  the  close  of  that  period,  as  was 
shown  by  Professor  Whitney  from  evidence  in  this  part  of  the  country. 
The  axis  of  upheaval  nearly  coincided  with  that  of  the  present  range. 

Besides  the  Tertiary  rocks  laid  down  there  exists  along  the  border  of 
the  Santa  Clara  Valley,  at  the  northern  edge  of  the  map,  a  small  quantity 
of  conglomerate,  composed  of  metamorphic  pebbles  embedded  in  an  arena- 
ceous matrix,  which  is  similar  to  the  Miocene  sandstone.  The  surface  here 
is  covered  with  a  Quaternary  soil,  and  none  of  the  conglomerate  could  be 
found  in  place,  nor  was  any  fragment  of  a  fossil  detected  in  it.  The  rock, 
which  is  of  no  great  importance,  may  be  a  remnant  of  Miocene ;  but,  were 
it  so,  it  would  be  strange  that  portions  of  it  should  not  have  been  found  at 
greater  altitudes,  raised  with  the  sandstones  by  the  Post-Miocene  upheaval. 
It  more  probably  represents  the  Pliocene,  but  I  do  not  dare  to  map  it  as 
such  in  the  absence  of  positive  evidence. 

Rhyoiite. — AVrhen  the  earliest  examinations  of  this  part  of  the  country 
were  made,  now  many  years  since,  the  serpentine  was  supposed  to  be 
eruptive,  and  at  later  dates  some  of  the  granular  metamorphic  rocks  have 
been  hastily  classed  as  trappean ;  but  at  the  time  of  my  examination  true 
eruptive  rocks  had  not  been  detected  near  New  Almaden.  This  is  not  so 
strange  as  it  might  seem,  for  it  happens  that  the  long  and  tolerably  regular 
dike  of  rhyolite,  which  many  observers  must  have  crossed  in  visiting  the 
district  from  San  Jose,  is  for  the  most  part  a  light-yellow,  finely  porous, 


314  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

tufa-like  substance,  which  at  a  little  distance  is  scarcely  distinguishable 
from  the  ordinary  Miocene  sandstone.  Only  in  a  few  small  patches  is  it 
found  in  a  dense  state  like  ordinary  andesitic  lavas.  The  microscope  and 
chemical  tests  show  that  it  is  quartzose,  glass-bearing  rhyolite.  The  im- 
portance of  this  dike  with  reference  to  the  ore  deposits  is  at  once  evident. 
It  would  be  entirely  unreasonable  to  suppose  that  this  dike  represents  the 
whole  of  the  lava  of  this  species  ejected  in  the  Coast  Ranges,  though  no 
other  mass  has  yet  been  detected.  If  the  physical  character  of  otlier  out- 
bursts is  similar  to  that  of  this  dike,  they  may  have  been  seen  repeatedly 
at  a  distance  without  recognition,  by  myself  as  well  as  by  others,  in  the 
course  of  reconnaissance  trips,  though  they  could  certainly  not  escape  detec- 
tion in  any  area  subjected  to  a  detailed  examination.  This  dike  not  only 
pit>ves  the  former  existence  of  volcanic  activity  in  this  district,  but  empha- 
sizes a  fundamental  structural  axis.  The  character  of  the  metamorphic 
rocks  shows  that  the  line  along  which  compression  and  upheaval  took  place 
in  the  early  Cretaceous  was  about  west  by  north,  east  by  south  The  fold- 
ing of  the  Tertiary  rocks  shows  that  compression  was  repeated  in  the  same 
direction  at  the  close  of  the  Miocene.  The  position  of  the  rhyolite  dike 
proves  that  the  dislocation  which  opened  a  passage  for  this  lava  again  fol- 
lowed a  similar  course.  As  for  the  age  of  the  rhyolite,  it  is  certainly  Post- 
Miocene,  for  had  it  been  earlier  it  must  have  shown  the  effects  of  the  Post- 
Miocene  uplift.  Had  the  lava  been  ejected  at  the  time  of  that  uplift,  it 
would  probably  have  been  so  eroded  that  the  croppings  would  present  a 
different  appearance,  for  the  tufaceous  modification  is  probably  superficial. 
It  is  possible,  however,  that  its  position  has  in  great  measure  protected  it 
and  that  during  the  Pliocene  it  was  covered  with  sediments.  As  a  rule,  the 
rhyolites  of  the  Pacific  slope  are  younger  than  the  andesites,  as  was  [jointed 
out  by  Baron  von  Richthofen,  and  if  this  rhyolite  is  younger  than  the  ande- 
sites of  Mt,  Diablo  and  of  Napa  County  it  is  Post- Pliocene ;  but  there  is  no 
direct  evidence  that  this  is  the  case.  On  the  whole,  the  probabilities  are. 
then,  that  the  rhyolite  is  recent  or  late  Pliocene,  but.  it  is  certainly  known 
only  that  it  is  not  older  than  the  Pliocene. 

Mine  minerals  and  rocks. TllC  Ol'eS    of    this  rCglOll   {ll'C   COlllpOSed    of   tllC   08118.1 

association  of  minerals  :  cinnabar  (sometimes  accompanied  by  a  little  native 


MINERALS  AT  NEW  ALMADEN.  315 

mercury),  pyrite,  quartz,  calcite,  and  dolomite,  and  more  or  less  closely 
associated  masses  of  bituminous  matter.  Accompanying  the  deposits  is  a 
small  amount  of  chalcedony  or  opal,  usually  black  in  color;  but  this  sub- 
stance is  much  less  abundant  here  than  in  the  greater  part  of  the  northern 
mines.  Dolomite  is  more  prevalent  as  a  gangue  mineral  here  than  in  most 
quicksilver  districts,  a  fact  probably  not  unconnected  with  the  unusual 
quantity  of  limestone  in  the  sedimentary  rocks.  The  croppings  of  the  de- 
posits are  to  a  large  extent  composed  of  dolomite  in  botryoidal  masses, 
instantly  seen  to  be  secretions,  and  not  sediments.  Besides  the  minerals 
enumerated,  Prof.  W.  P.  Blake  reported  mispickel  in  the  upper  working 
of  the  New  Almaden.1  This  mineral  was  extremely  abundant  in  the  great 
Peruvian  mine  and  its  existence  at  New  Almaden  is  not  at  all  improbable. 
No  one  seems  to  have  observed  it  here  since  1854,  however;  for  Prof.  B. 
Silliman2  in  1804,  Mr.  Goodyear3  in  1871,  and  my  party  in  1885  failed  to 
meet  with  it.  Neither  is  it  mentioned  by  Mr.  G.  Holland.4  Professor  Blake 
also  states  that  gold  has  frequently  been  found  in  small  quantities  in  this 
mine.  This,  too,  is  far  from  improbable,  but  it  has  not  been  verified 

The  rocks  associated  with  cinnabar  in  this  district  include  every 
variety  of  the  metamorphic  series.  Where  the  rock  happens  to  be  a  per- 
meable sandstone,  impregnations  have  resulted.  Elsewhere  the  ore  seems 
to  occur  exclusively  in  crevices  in  the  rock,  nor  are  the  cracks  invariably 
filled,  so  that  quartz  and  carbonates  frequently  show  surfaces  covered  with 
crystal  faces.  In  some  cases  quartz  reddened  throughout  by  cinnabar 
occurs  in  this  manner.  I  was  unable  to  perceive  any  indication  that  ore 
had  been  deposited  by  substitution  or  that  the  rock  had  influenced  the 
deposition  of  ore  by  its  chemical  properties.  Ore  is  found  with  nearly 
equal  frequency  in  contact  with  various  rocks  and  the  existence  of  fissures 
appears  to  have  been  the  nccessarv  and  sufficient  condition  for  the  deposi- 
tion of  cinnabar  and  gangue  minerals.  The  rock,  then,  influences  the 
occurrence  of  ore  mechanically,  though  indirectly.  Where  disturbance  of 
the  country  resulted  in  the  formation  of  open  fissures  or  of  ground  present- 

1  Am.  Jour.  Sci.,  2d  series,  vol.  17, 1854,  p.  438. 

II. id.,  vo].:;s,  H(M,p.  192. 

:  (':!•(>}.  Survey  California,  Geology,  vol.2,  appendix,  p.  99. 
*  Anniile.s  il>-s  mines,  vol.  14,  1.^78,  p.  :!84. 


316  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

ing  a  large  amount  of  interstitial  space,  ore  bodies  were  formed,  but  where 
the  rock  yielded  to  stress  as  a  plastic  mass  no  room  was  left  for  ore. 

Aitas.— The  ore  in  the  New  Almaderi  mine  seems  never  to  occur  except 
close  to  evidences  of  faulting.  This  evidence  consists  in  the  presence  of 
layers  of  attrition  products,  so-called  clays,  full  of  slickensides  and  of  frag- 
ments of  rocks  more  or  less  rounded  by  attrition.  These  lavers  of  clav 

J  V  4 

usually  occur  on  the  hanging  side  of  deposits  and  are  known  to  the  miners 
as  altas,  the  Spanish  term  for  hanging  walls.  The  clays  are  impermeable  to 
solutions  and  the  ore  usually  forms  on  their  lower  side,  as  if  the  cinnabar 
had  ascended  and  been  arrested  by  the  alias.  That  the  solutions  really 
took  this  course  is  clearly  shown  by  the  phenomena  of  other  quicksilver 
districts,  as  well  as  by  the  relations  observed  in  the  New  Almaden  mine 
The  miners  very  properly  follow  seams  of  alta  in  their  search  for  ore. 
Sometimes,  however,  a  second -mass  of  ore  exists  on  the  hanging  side  of 
the  clay  and  is  again  limited  by  a  second  layer  of  alta,  as  I  have  myself 
observed.  Such  occurrences  are  to  be  expected  in  a  country  so  irregularly 
disturbed  as  this.  The  alta  is  not  a  definite  substance,  though  it  is  usually 
a  dark  or  black  mass,  readily  distinguishable  even  in  hand  specimens  from 
the  country  rock.  It  is  simply  triturated  country  rock  and  varies  in  com- 
position'with  the  material  from  which  it  has  been  produced.  Its  black 
color  is  in  part  due  to  the.  presence  of  manganese.  These  layers  of  clay 
correspond  exactly  to  those  which  were  met  with  in  the  upper  portion  of 
the  Comstock  lode  and  against  which  many  bonanzas  were  found  to  rest. 
The  evidence  of  movement  in  the  New  Almaden  mine  is  not  confined  to 
clays.  Where  the  opposing  walls  were  so  nearly  parallel  that  no  consider- 
able quantity  of  trituration  took  place,  polishing  occurred,  and  some  of  the 
slickensides  met  with  are  as  brilliantly  polished  as  if  the  work  had  been 
done  by  a  lapidary. 

Form  of  the  New  Almaden  ore  bodies While  tllC  evidence  of  tll6  existence  of  a  fis- 

sure  system  is,  if  possible,  more  abundant  in  the  New  Almaden  mine  than 
in  most  other  quicksilver  deposits  of  the  Pacific  slope,  the  deposits  them- 
selves are  of  various  types.  The  commonest  is  the  reticulated  mass,  or 
stockwork,  consisting  of  irregular  bodies  of  broken  rock  into  which  solutions 
of  cinnabar  and  gangue  minerals  have  filtered,  cementing  the  fragments  to- 


FISSUliE  SYSTEM.  317 

gether  with  ore.  Where  the  disturbance  has  been  less  extensive  and  irreg- 
ular, clean-cut  fissures  may  sometimes  be  seen  filled  with  ore,  and  these 
can  only  bo  classed  as  veins,  though  they  are  not  persistent.  As  already 
mentioned,  impregnations  also  exist  where  the  ore-bearing  solutions  havo 
encountered  permeable  sandstones. 

The  classification  of  the  various  portions  of  such  a  deposit  under  various 
names  seems  to  me  of  very  little  interest,  excepting  as  it  serves  to  a  certain 
extent  as  a  basis  of  comparison  between  ore  deposits  of  different  regions. 
It  is  not  long  since  it  was  customary  to  maintain  that  the  deposits  of  cinna- 
bar were  very  different  in  character  from  those  of  other  ores  and  that  the 
genesis  of  quicksilver  deposits  was  essentially  unlike  that  of  other  metals. 
I  have  taken  some  pains  therefore  to  show  that  no  distinction  can  be  main- 
tained as  to  form  between  the  ore  bodies  of  the  quicksilver  mines  and  well 
recognized  types  of  gold,  silver,  and  copper  deposits.  The  only  important 
mode  of  occurrence  of  ores  which  I  have  not  encountered  in  the  quicksilver 
mines  is  that  of  replacement.  Lead  ores  have  certainly  in  some  cases  re- 
placed limestone  molecule  for  molecule.  According  to  Prof,  von  Groddeck, 
cinnabar  ore  at  Mt,  Avala,  in  Servia,  has  replaced  serpentine  in  a  similar  man- 
ner. Others  also  have  been  led  to  suppose  analogous  substitutions  at  Al- 
inaden  and  at  Idria,  but  I  have  not  met  with  them  at  those  mines  or  any- 
where in  California. 

Existence  of  a  fissure  system. — While  the  reference  of  deposits  to  different  heads 
of  more  or  less  artificial  classifications  is  only  of  indirect  interest,  a  compre- 
hension of  the  fundamental  structural  relations  of  the  ore  bodies  of  a  mine 
is  of  the  utmost  importance  to  its  conduct.  From  any  one  accessible  stope 
of  the  New  Almaden  mine  it  is  evident  that  the  country  has  been  intersected 
by  fissures,  that  energetic  motion  has  taken  place  along  these  fissures,  that 
the  adjoining  rock  masses  have  been  shattered  more  or  less  irregularly,  and 
that  solutions  entering  the  ground  have  deposited  ore  in  such  spaces  as  were 
vacant.  It  is  also  apparent  from  the  relations  of  the  ore  to  the  clay  that  the 
solutions  have  entered  from  below,  and  it  is  almost  a  necessary  inference 
that  the  fissures  served  as  channels  of  ingress  for  the  solutions.  These  con- 
clusions may  be  drawn  in  each  of  as  many  chambers  as  the  observer  can 


318  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC!  SLOPE. 

reach,  and  he  will  find  nothing  to  conflict  with  them  in  any  portion  of  the 
mine. 

Certain  features  must  be  common  to  the  ore  bodies  taken  singly  and  to 
the  ore-bearing  ground  as  a  whole.  It  would  be  impossible  to  suppose  that 
each  atockwork  has  an  independent  fissure  system,  and  a  mere  glance  at  the 
mine  maps  shows  that  a  connection  between  them  exists.  It  is  also  a  his- 
torical fact  that  the  thin  seams  of  ore  (stringers  or,  as  the  Spanish  miners 
call  them,,  hilos)  have  led  from  one  ore  chamber  to  another.  There  must  be 
a  general  fissure  system,  in  subordination  to  which  the  various  ore  bodies 
are  arranged,  and  this  system  must  stand  in  the  closest  relations  to  the  gen  - 
eral  geology  of  the  country.  Such  a  system  can  result  only  from  a  some- 
what widespread  disturbance  and,  it  is  superfluous  to  remark,  must  have  been 
formed  according  to  ordinary  mechanical  laws.  If  the  rock  of  the  country 
were  thoroughly  homogeneous  and  were  level  at  the  surface,  a  fissure  caused 
by  a  simple  disturbance  would  follow  a  straight  line  and  would  pass  over 
at  its  extremities  into  a  fold.  Under  a  sufficient  horizontal  stress  such  a 
country  would  show  a  system  of  parallel  fissures  passing  into  a  common 
fold  at  each  end.  Fissures  thus  tend  to  straight  lines  and  parallel  systems, 
but  this  tendency  is  modified  by  inequalities  in  the  properties  of  the  rock 
and  in  the  configuration  of  the  surface.  It  is  often  difficult  to  decipher 
the  fundamental  fissure  system  in  a  country  of  heterogeneous  character, 
but  this  does  not  seem  to  be  the  case  at  New  Almaden. 

The  distribution  of  serpentine,  the  average  strike  of  the  nietamorphic 
strata,  the  compression  of  the  Miocene  beds,  the  position  of  the  rhyolite 
dike,  and  the  trend  of  the  range,  in  short  the  whole  structural  geology  of 
the  region  shows  that  the  fundamental  axis  of  disturbance  must  have  a 
direction  which  is  approximately  northwest  and  southeast.  It  is  along  a 
fissure,  or  a  system  of  parallel  fissures,  taking  this  general  direction,  but 
more  or  less  deflected  by  local  causes,  that  ore  might  be  expected  to  occur 
in  such  a  district.  It  is  on  such  a  line  that  the  New  Almaden,  Enriquita, 
and  Guadalupe  deposits  occur.  In  the  New  Almaden  mine  itself,  also,  there 
appear  to  me  clear  evidences  of  a  fundamental  fissure  system. 

Plans  and  sections  of  the  New  Almaden TllC  SUl'faCe  and   tllO   WOl'kingS  of  tllC  NeW 

Almaden  mine  have  been  surveyed  with  the  utmost  care  by  the  officers  of 


SECTIONS  OF  THE  NEW  ALMADEN.  319 

the  Quicksilver  Mining  Company,  and  data  exist  for  the  construction  of 
any  desired  sections.  A  fine  opportunity  is  thus  afforded  for  a  study  of  the 
structure  of  this  very  important  deposit,  and  it  has  seemed  to  me  worth 
while  to  illustrate  the  occurrence  very  fully  by  plans  and  sections.  The 
mine  maps  and  sections  which  I  selected  as  best  adapted  to  show  the  struct- 
ure were  prepared  for  me  from  plans  and  notes  in  the  office  of  the  company 
by  Mr.  Frank  Reade,  who  was  surveyor  of  the  mine  at  the  time  of  my 
examination  and  who  formerly  assisted  me  in  studying  the  Comstock  Lode. 
The  ore  deposits  being  in  my  opinion  comparatively  recent,  the  rela- 
tions between  their  distribution  and  the  present  topography  of  the  surface 
are  of  interest.  On  Atlas  Sheet  VIII  the  plan  of  the  known  ore  bodies  is 
shown  beneath  a  contour  map  of  the  surface.  It  will  be  at  once  remarked 
that  these  ore  bodies  are  divisible  into  four  groups.  Two  of  them,  reached 
respectively  by  the  Washington  and  Cora  Blanca  shafts,  seem  to  be  isolated. 
The  other  two  groups,  upon  which  the  main  mine  has  been  opened,  are  very 
closely  connected.  The  more  important  group  of  the  ore  bodies  of  the 
main  mine  reaches  from  the  top  of  the  Mine  Hill  nearly  to  the  Santa  Isabel 
shaft  and  is  substantially  continuous  for  the  entire  distance.  The  croppings 
at  which  Castillero  and  others  before  him  found  cinnabar,  as  was  narrated  in 
Chapter  I,  were  at  the  top  of  Mine  Hill.  A  monument  at  this  point  is  used 
as  the  datum  to  which  the  contours  and  mine  levels  are  referred.  The  other 
group  of  ore  bodies  of  the  main  mine  lies  to  the  east  of  the  Randol  shaft. 
I  shall  have  frequent  occasion  to  distinguish  these  two  sets  of  ore  bodies 
and  shall  refer  to  them  as  the  north  and  south  groups.  This  map  is  printed 
on  a  scale  of  300  feet  to  the  inch  and  the  contours  are  drawn  at  vertical 
intervals  of  10  feet.  The  plan  of  the  workings  is  given  on  Atlas  Sheet  IX, 
this  and  the  succeeding  sheets  being  drawn  on  a  scale  of  150  feet  to  the 
inch,  or  double  that  of  the  topographical  map  on  Sheet  VIII.  The  highly 
complex  structure  of  the  separate  ore  bodies  is  very  apparent  from  this  plan 
as  well  as  the  existence  of  certain  surfaces  along  which  the  ore  bodies  are 
grouped.  The  colors  and  figures  make  explanations  needless.  I  have  not 
tried  to  indicate  on  this  plan  or  on  the  sections  the  character  of  the  wall  rocks, 
for  nothing  could  result  from  such  an  effort.  The  entire  mass  of  the  country 
rocks  consists  of  metamorphosed  sediments.  Every  stage  of  metamorphisin 


320  QUICKSILVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

is  represented,  and  pseudodiorite,  pseudodiabase,  phtlianites,  sandstone,  sliale, 
and  serpentine  are  mingled  in  inextricable  confusion. 

Atlas  Sheet  X  shows  a  section  taken  along  the  course  of  the  south  group 
of  bonanzas.  The  line  on  which  the  section  is  made  is  shown  on  the  mine 
map  and  was  selected  with  a  view  of  illustrating1  the  continuity  of  ore  from 
the  surface  at  the  top  of  Mine  Hill  to  the  lowest  workings.  The  group  of 
ore  bodies  thus  intersected  is  for  the  most  part  distinct  from  that  to  the  east 
of  the  Randol  shaft.  It  is  manifest  from  this  section  that  a  fissure  extends 
from  the  lower  workings  to  the  top  of  Mine  Hill,  a  vortical  distance  of 
about  2,000  feet,  and  that  ore  has  been  deposited  almost  continuously  along 
its  entire  course.  This  fissure  is  remarkably  sinuous  in  vertical  section,  and 
a  long  tongue  of  ground  north  of  Mine  Hill  has  manifestly  moved  north- 
ward sufficiently  to  leave  space  for  the  deposition  of  ore.  If  one  considers 
the  character  of  the  disturbance  to  which  the  fissure  must  owe  its  origin,  it 
appears  almost  certain  that  this  tongue  of  country  rock  overlying  the  fissure 
cannot  have  remained  intact.  One  would  expect  to  find  one  or  more  fis- 
sures intersecting  it  in  a  direction  more  nearly  vertical  than  the  south  ore 
channel,  because  the  tenacity  implied  in  the  movement  of  the  entire  hang- 
ing country  without  fracture  would  be  improbably  great,  even  were  the  rock 
much  firmer  than  the  materials  of  which  the  Coast  Ranges  are  chiefly  com- 
posed. Such  a  fissure  intersecting  the  hanging  country  really  exists,  and  a 
trace  of  it  may  be  perceived  on  this  section  from  the  1,500-foot  level  down- 
ward, where  the  stopes  show  that  the  ore  occurs  on  parallel  lines.  The 
line  of  the  northerly  stopes  in  this  region  if  continued  upward  would  reach 
the  surface  near  the  point  at  which  the  Randol  shaft  appears  projected. 

On  Atlas  Sheet  XI  two  sections  are  shown,  cutting  the  northern  portion 
of  the  mine  on  parallel  north  and  south  planes.  One  of  them  is  taken 
through  the  Randol  shaft  and  the  other  350  feet  west  of  it.  The  two  are 
to  be  considered  together  and  as  if  they  were  superimposed.  The  western 
section  shows  the  same  group  of  bodies  as  is  depicted  upon  Sheet  X,  but 
cut  at  a  different  angle.  The  relations  of  the  section  on  Sheet  XI  are  most 
easily  appreciated  by  reference  to  their  traces  on  the  mine  map  (Sheet  IX). 
The  eastern  section,  through  the  shaft,  on  Sheet  XI  is  very  different.  It 
shows  only  the  edge  of  the  south  ore  channel,  or  of  that  series  of  deposits 


SECTIONS  OF  THE  NEW  ALMADEN.  321 

which  crops  out  on  Mine  Hill.  To  this  series  belong  the  various  Santa  Rita 
"  labores  "  exhibited  on  the  southern  part  of  the  section,  and  the  series  of 
winzes  extending  from  the  Santa  Rita  to  the  1,400-foot  level  of  the  Randol 
shaft,  showing  here  and  there  a  small  slope,  was  sunk  along  the  course 
of  the  same  fissure.  The  main  stopes  on  this  section  are  on  the  north  fis- 
sure, which  divides  the  great  body  of  rock  forming  the  hanging  country 
of  the  south  fissure  from  the  region  north  of  the  mine. 

Another  view  of  the  two  fissures  is  shown  on  Atlas  Sheet  XII,  where 
they  are  intersected  by  an  east  and  west  vertical  plane.  To  the  right  ap- 
pears the  south  ore  channel,  including  the  O'Brien,  Don  Federico,  and  other 
bodies  ;  to  the  left  is  the  north  fissure. 

Existence  of  two  principal  fissures. — The  existence  and  position  of  the  two  fissures 
are  not  so  evident  and  clear  as  would  appear  from  the  foregoing  notes.  The 
ore  bodies  lie  upon  complex  curved  surfaces.  The  result  is  that  no  vertical 
plane  intersects  both  fissures  at  right  angles  throughout,  and  no  single  sec- 
tion affords  indubitable  evidence  of  two  fissures.  Views  similar  to  those 
shown  in  the  sections  might  be  given  of  two  channels  along  a  single,  doubly 
curved  surface.  Could  one  but  represent  the  fissures  by  contours,  the  en- 
tire structure  would  be  shown  in  three  dimensions  and  would  not  be  ambig- 
uous. A  certain  approximation  to  this  result  can  be  reached.  As  was 
mentioned  above,  the  fissures  are  marked  by  clay  seams  or  altas.  It  oc- 
curred to  me  that  if  one  could  lay  down  all  the  alta  seams  followed  in 
the  explorations  the  result  would  closely  resemble  a  contour  map  of  the 
fissures.  Mr  Reade,  with  the  assistance  of  other  officers,  has 'compiled  all 
the  information  available  regarding  the  occurrence  of  altas  in  the  northern 
part  of  the  mine,  and  they  are  shown  on  the  same  scale  as  the  mine  map  on 
Atlas  Sheet  XIIL  The  result,  however,  requires  some  discussion  because 
of  the  irregularity  of  the  lines  and  the  distance  which  sometimes  intervenes 
between  the  two  ore  channels.  At  the  northwest  the  fissures  come  nearly 
together,  and  on  the  1,930,  the  1,850,  and -the  1,735  foot  levels  it  is  plain 
from  the  position  of  the  altas  that  there  are  at  least  two  nearly  parallel 
fissures.  On  the  1,650  the  alta  forks,  probably  indicating  the  existence  of 
two  fissures  connected  by  a  diagonal  cross-course,  for  on  the  1,5-10  and 
again  at  the  1,440  there  are  two  altas  nearly  parallel  and  at  a  considerable 

MON  XIII 21 


322  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

distance  from  one  another.  On  the  1,850  (1,832  to  1,847)  it  is  the  north- 
erly alta  which  extends  to  the  north  group.  The  same  is  true  of  the  clays 
on  the  1,735,  and  on  the  1,650  it  is  also  the  north  fork  of  the  alta  which 
has  been  followed  to  the  neighborhood  of  the  Randol  shaft.  On  the  1,550 
(1,540  to  1,547)  there  are  three  lines  of  alta,  two  of  which  are  to  the  south- 
west and  one  to  the  northeast.  From  the  continuities  just  mentioned  on 
the  three  levels  below  this  it  is  evident  that  the  northerly  alta  of  the  1,540 
in  the  southwest  region  answers  to  the  alta  in  the  north  group  of  ore  bodies, 
and  to  emphasize  this  relation  I  have  connected  the  two  altas  by  a  straight 
dotted  line.  A  precisely  similar  relation  exists  on  the  1,440.  Thus  for  a 
vertical  interval  of  500  feet  there  is  abundant  evidence  of  two  fissures,  the 
outer  or  more  northerly  of  which  leads  into  the  north  group  of  ore  cham- 
bers. The  inner  or  more  southerly  fissure  is  certainly  that  upon  which  ore 
has  been  followed  from  the  top  of  Mine  Hill,  as  may  clearly  be  seen  by  ref- 
erence to  the  section  of  this  channel  on  Atlas  Sheet  X.  The  southerly  or 
inner  altas  on  the  1,540  and  1,440  levels  form  the  hanging  wall  of  ore  body 
XLI,  which  appears  on  Atlas  Sheet  X,  and  this  section  shows  that  from  this 
body  to  the  top  of  Mine  Hill  the  ore  is  substantially  continuous.  The  outer 
or  northerly  alta  appears  on  Atlas  Sheet  X  as  the  hanging  wall  of  the  body 
XLVIII.  These  same  altas  in  the  north  group  overlie  the  bonanzas  known 
as  XXI,  XLIV,  XX,  which  appear  on  the  section  through  the  Randol  shaft 
(Atlas  Sheet  XI),  and  from  this  section  it  is  manifest  that  the  fissure  cany- 
ing  these  bonanzas  is  continuous  up  to  the  900-foot  level.  Referring  again 
to  the  plan  of  the  altas  (Atlas  Sheet  XIII),  it  is  seen  that  the  two  groups 
of  ore  bodies  are  so  far  apart  between  the  1,440  and  the  1,050  that  from 
this  plan  alone  no  certain  result  could  be  reached  as  to  the  distinctness  of 
the  fissures  within  this  interval.  The  lines  of  altas  aro  very  tortuous  as 
well  as  distant,  and  without  the  aid  of  the  sections  it  might  seem  quite  pos- 
sible that  the  altas  of  the  same  level  were  continuous  in  the  two  groups; 
but  in  the  foregoing  I  have  sluown  that  each  of  these  fissures  for  the  inter- 
val between  the  1,440  and  the  1,050  continues  in  depth  and  that  at  lower 
levels  the  fissures  are  distinct.  It  is  true  that  the  fissures  might  come  to- 
gether above,  though  this  would  be  an  unusual  structure.  But  on  the  950 


FISSURES  OF  THE  NEW  ALMADEN.  323 

the  altas  of  the  two  groups  once  more  assume  a  position  of  approximate 
parallelism,  which  shows  that  they  remain  distinct  throughout. 

Another  test  of  the  distinctness  of  the  fissures  can  be  applied,  and, 
indeed,  one  which  is  of  no  small  importance  for  the  mine.  The  average 
strike  of  the  north  group  in  its  upper  portion  is  on  a  line  not  far  from  S. 
50°  W.  magnetic,  and,  as  shown  by  the  north  and  south  section  through 
the  shaft,  if  the  north  fissure  were  continuous  it  would  reach  the  surface 
about  four  hundred  feet  south  of  the  Randol  shaft.  Having  arrived  at  this 
conclusion,  I  examined  the  surface,  and  did  in  fact  find  a  line  of  dolomitic, 
botryoidal  croppings  north  of  the  road  leading  from  the  office  to  the  Randol 
shaft  above  the  Randol  group  of  bonanzas,  and  which  seemed  to  strike  for 
other  croppings  on  which  a  little  tunnel  has  been  opened  about  four  hun- 
dred and  fifty  feet  south  magnetic  from  the  shaft.  These  croppings  thus 
strike  very  nearly  in  the  same  direction  as  the  altas  of  the  Randol  group 
of  ore  bodies  on  the  1,050-foot  level,  and  are  very  close  to  the  position 
indicated  for  a  cropping  of  this  fissure.  In  my  opinion  they  represent 
such  a  cropping  and  complete  the  proof  that  the  New  Almaden  mine  pos- 
sesses two  important  fissures,  along  one  of  which  the  south  group  of 
bonanzas  has  been  followed  from  the  surface,  while  the  north  group  lies 
upon  the  other.  One  fissure  underlies  the  great  tongue  of  hanging  coun- 
try, the  other  intersects  it. 

ore  in  the  inclosed  wedge. — Between  the  two  principal  fissures  a  wedge  of 
country  rock  exists.  It  is  not  uncommon  for  great  masses  of  this  description 
to  be  inclosed  on  both  sides  by  ore-bearing  fissures.  Such  was  the  case  on 
the  Comstock  and  also  in  the  Ruby  Hill  mines  at  Eureka,  Nev.  Ground 
thus  inclosed  is  seldom  solid  and  subsidiary  fissures  leading  into  it  are  often 
ore  bearing.  In  the  New  Almaden  mine  the  ore  is  not  confined  to  well  de- 
fined fissures.  It  is  true  that  ore  can  be  followed  from  the  top  of  Mine  Hill 
downward  to  a  depth  of  1,600  feet  practically  without  a  break;  but  the  sec- 
tions show  that  at  many  points  the  fissures  are  systems  of  associated  open- 
ings rather  than  simple  ruptures.  The  north  and  south  section  through  the 
Randol  shaft  shows  a  section  of  the  Velasco,  Theatre,  and  several  of  the 
Santa  Rita  bodies,  which  is  especially  illustrative  of  this  structure.  The 
section  shows  that  the  wedge  of  ground  between  the  principal  fissures  is 


324  QUiCKSILVEE  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

not  a  solid  mass,  but  that  subordinate  fissures  and  ore  channels  exist  in  it. 
This  would  be  still  more  evident  were  all  the  ore  bodies  represented.  Those 
which  have  been  exploited  since  systematic  work  was  begun  are,  I  believe, 
all  accurately  given,  but  in  the  early  days  there  were  many  openings, 
resembling  burrows  rather  than  mines,  excavated  from  the  surface  between 
the  Randol  shaft  and  the  top  of  Mine  Hill.  Mr.  Reade  has  shown  many 
of  the  dumps  of  these  old  workings  on  Atlas  Sheet  VIII.  They  produced 
considerable  quantities  of  ore.  One  of  them,  the  Juan  Vega,  which  appears 
on  the  plan  but  not  on  the  sections,  I  was  able  to  explore.  The  stopes  were 
of  considerable  size  and  the  ore  appears  to  have  been  very  rich.  It  was 
associated  with  masses  of  dolomite  similar  to  those  found  at  the  surface  as 
croppings,  but  which  are  not  met  with  in  the  lower  levels.  Evidently  fis- 
sures carrying  ore  in  solution  must  have  readied  the  Juan  Vega  and  other 
similar  deposits.  These  fissures  must  have  connected  with  great  ore  chan- 
nels, and  must  therefore  intersect  the  wedge  of  country  rock. 

The  wedge  of  rock  between  the  two  principal  fissures  has  contained 
ore  bodies  and  the  fissures  leading  to  them  must  penetrate  the  wedge  through 
and  through.  The  entire  mass  should  be  regarded  as  potentially  ore  bear- 
ing and  should  be  explored.  It  is  not  in  the  least  likely  that  all  the  ore 
which  it  contains  is  known  and,  if  other  bodies  are  encountered,  they  will 
be  mined  at  a  greater  profit  than  similar  bodies  at  lower  levels.  This  mass 
arid  the  lateral  extensions  of  the  main  fissures  constitute  the  promising 
ground  in  the  mine.  At  the  lowest  levels  reached  there  is  little  ore.  There 
is  no  known  reason  why  bodies  of  cinnabar  should  not  be  found  at  still 
greater  depths,  but  I  do  not  regard  it  as  probable  that  the  ore  chambers 
beneath  the  2,000-foot  level  will  be  as  frequent  as  they  were  above  Some 
further  comments  on  the  fissure  system  of  this  mine  will  be'made  below. 

Cora  Blanca  and  Washington  deposits.— -The     WOl'luUgS    of     tllC     WasllillgtOll     shaft, 

which  were  formerly  known  as  the  San  Francisco  mine,  are  connected 
with  the  main  mine  of  New  Almaden,  but  the  deposits  were  not  being 
worked  during  my  visit.  The  association  of  minerals  and  rocks  is  entirely 
similar  to  that  of  the  main  mine,  and  the  deposits  are  also  accompanied  by 
clay  seams  or  altas.  The  position  of  the  deposits  is  shown  on  Atlas  Shifts 
VIII,  IX,  and  X.  Ore  has  been  followed  in  the  workings  to  a  depth  of 


OTHER  DEPOSITS  NEAR  NEW  ALMADEN.  325 

850  feet  below  the  summit  of  Mine  Hill,  but  below  that  level  no  ore  bodies 
have  as  yet  been  met  with.  The  strike  of  these  deposits  is  at  an  angle  of 
over  70°  to  the  deep  fissure  of  the  New  Almaden,  and  both  fissures  stand 
at  considerable  angles  to  the  main  axis  of  uplift. 

Near  the  New  Almaden  and  the  Washington  is  the  Cora  Blanca  mine, 
the  position  of  which,  with  a  horizontal  projection  of  the  ore  bodies,  is 
shown  on  Atlas  Sheet  VIII.  Portions  of  it  were  accessible  to  me,  but  no 
work  was  being  done  upon  it.  Though  the  rocks  inclosing  this  deposit  are 
members  of  the  metamorphic  series  they  are  less  modified  than  usual,  and 
in  part  are  but  little  contorted,  though  standing  at  a  high  angle.  One  of 
the  strata,  which  is  usually  close  to  the  ore,  is  a  magnesian  limestone. 
Some  native  quicksilver  was  found  in  the  mine.  The  gangtie  minerals 
accompanying  the  cinnabar  are  almost  exclusively  carbonates.  There  are 
clays  and  evidences  of  disturbances  in  the  Cora  Blanca,  but  less  marked 
than  in  the  New  Almaden.  The  ore-bearing  solutions  have  followed  the 
bedding  for  the  most  part,  and  in  places  the  deposits  can  be  classed  only 
as  a  bedded  vein;  but  not  infrequently  the  ore  crosses  laminaj  and  often 
fills  chambers  adjacent  to  the  main  ore-bearing  surface.  These  are  in  part 
reticulated  masses  and  in  part  impregnations  in  sandstones.  The  ore  was 
followed  to  a  depth  of  750  feet  below  the  summit  of  Mine  Hill.  The  strike 
of  this  deposit  is  about  N.  18°  W.  magnetic,  or  very  nearly  true  north  and 
south.  The  direction  has  doubtless  been  influenced  by  the  fact  that  the 
partings  between  the  beds  offered  a  comparatively  slight  resistance  to  rupt- 
ure. The  average  dip  is  about  40°  to  the  west. 

The  Endquita.— The  Enriquita  mine  is  also  on  the  property  of  the  company 
which  owns  the  deposits  described  above.  It  has  long  been  abandoned  and 
no  part  of  the  deposits  is  accessible.  The  ore-bearing  ground  was  about 
five  hundred  feet  in  length  and  had  an  extreme  width  of  about  sixty  feet, 
the  dip  being  nearly  vertical.  From  a  manuscript  report  of  Mr.  Louis  Ja- 
nin,  which  he  has  kindly  shown  me,  I  see  that  the  ore  was  found  in  lime- 
stone inclosed  on.  both  sides  by  serpentine.  The  ore  formed  rich  pockets, 
connected  by  stringers,  and  the  lowest  body,  the  San  Jose,  was  the  richest 
of  all.  The  mine  possessed  reduction  works  and  in  a  short  time  yielded 


326  QUICKSILVEIJ  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

metal  worth  $350,000.  It  was  producing  in  18GO  and  is  said/  to  have 
yielded  about  nine  thousand  flasks. 

The  Guadaiupe. — Over  fifty  thousand  flasks  of  quicksilver  have  been  pro- 
duced from  the  Guadalupe,  which  was  closed  at  the  time  of  my  visit,  though 
it  had  been  working  in  the  preceding  year.  Cinnabar  has  been  found  at  a 
great  number  of  points  on  this  property  over  an  area  of  about  a  half  a  mile 
square.  -The  only  deposit  of  large  size  detected  cropped  out  about  one 
hundred  and  fifty  feet  north,  of  the  creek  and  has  been  followed  down- 
ward for  over  seven  hundred  feet.  The  strike  of  the  main  body  was  about 
east  and  west  magnetic ;  but  to  the  east  seams  have  been  followed  on 
a  more  northerly  course  which  led  to  small  bodies  of  ore.  The  dip  is 
southerly  and  the  greater  part  of  the  mine  lies  south  of  the  creek.  The  ore 
and  the  associated  substances  are  said  to  have  resembled  those  of  New 
Almaden,  but  I  have  been  unable  to  obtain  any  particulars  of  interest.  A 
small  quantity  of  ore  was  obtained  from  the  "  Office  mine,"  a  small  excava- 
tion on  a  cropping  some  two  hundred  and  fifty  feet  north  of  that  of  the 
main  mine.  Some  of  the  other  numerous  superficial  workings  have  also 
yielded  ore. 

These  excavations  have  obscured  rather  than  revealed  the  structure  of 
the  country,  and  I  was.  unable  to  make  observations  sufficiently  definite  to 
justify  important  conclusions.  It  certainly  is  improbable  that  the  resources 
of  the  locality  are  exhausted.  The  most  evident  course  to  be  pursued  is 
further  exploration  along  the  fissures  developed  by  the  main  mine.  Were 
the  old  tunnels  and  superficial  workings  which  dot  the  surface  cleaned  out, 
it  is  also  possible  that  a  careful  study  would  reveal  other  fissures  which 
might  be  ore  bearing  in  depth ;  but  there  is  no  certainty  that  the  search 
for  ore  bodies  would  prove  successful.  Quicksilver  deposition  in  the  Coast 
Ranges  has  been  very  irregular  and  study  of  the  geological  phenomena 
shows  that  this  is  an  almost  necessary  consequence  of  the  structure.  The 
only  way  for  quicksilver  miners  to  keep  up  the  value  of  their  property  is 
to  study  the  fissure  system  with  the  most  earnest  attention  from  day  to  day 
and  to  do  their  prospecting  while  in  bonanza.  Prospecting  when  all  the  vis- 
ible ore  has  been  extracted  and  the  old  workings  have  become  inaccessible 
is  little  better  than  guess-work  and  seldom  meets  with  much  reward.  It  is 


THE  GUADALUPE.  327 

only  under  exceptional  conditions  that  ore  bodies  can  be  foreseen  in  the 
quicksilver  mines,  and  predictions  as  to  the  quantity  of  ore  in  these  mines, 
excepting  so  far  as  the  ore  is  in  sight,  ore  entirely  valueless. 

Minor  deposits. — In  addition  to  the  mines  UpDn  which  notes  have  been  given 
above,  there  are  a  number  of  workings  which  have  yielded  cinnabar  in 
quantities  of  little  or  no  commercial  importance,  but  which  throw  some  light 
on  the  structure  of  the  country  through  their  position  relatively  to  the  more 
developed  deposits.  The  America,  to  the  westward  of  the  New  Almaden 
mine  and  a  little  south  of  the  ridge,  showe'd  two  small  ore  bodies.  From 
the  plan  of  the  drifts  it  would  appear  that  clays  running  to  the  northeast 
were  followed.  The  Providentia,  one  quarter  of  a  mile  from  the  Enriquita, 
in  the  direction  of  the  New  Almaden,  yielded  ore  of  excellent  quality,  as  I 
learn  from  Mr.  Janin.  The  San  Antonio  mine  was  half  a  mile  northwestward 
from  the  Enriquita,  on  the  hillside  northeast  of  Los  Capitancillos  Creek,  and 
the  San  Mateo  was  a  quarter  of  a  mile  farther  in  the  same  direction  and 
in  a  similar  topographical  position. 

A  mass  of  black  opal,  such  as  is  so  often  associated  with  cinnabar  in 
California,  exists  about  6,400  feet  north  magnetic  from  the  Enriquita,  be- 
tween the  isolated  patch  of  rhyolite  and  the  continuous  dike.  I  am  not 
aware  that  cinnabar  has  been  detected  at  this  point,  but  it  would  not  be 
surprising  if  search  were  to  disclose  at  least  a  trace  of  ore. 

Age  and  genesis  of  the  deposits. — The  croppings  of  Mine  Hill  have  been  exposed 
for  a  long  time  and  there  is  a  considerable  quantity  of  cinnabar  in  the  sur- 
face soil  of  the  hill.  The  deposits  have  been  formed  since  any  violent  dis- 
turbance of  the  country  took  place,  however,  for  there  are  mere  traces  of 
dislocation  in  the  ore  bodies.  The  eruption  of  rhyolite  must  have  been 
accompanied  by  very  considerable  movement  of  the  country,  and,  had  the 
deposits  existed  before  the  formation  of  the  dike,  they  could  hardly  have 
escaped  dislocation.  There  are  no  unquestionably  Pliocene  strata  at  New 
Almaden,  but  beds  of  this  age  have  been  considerably  disturbed  both  to 
the  north  and  to  the  south,  though  at  distances  of  a  number  of  miles.  It  is 
very  probable,  but  not  certain,  therefore,  that  the  deposits  are  Post-Pliocene, 
while  it  is  certain  that  they  are  not  Pre-Pliocene. 


328  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Ore  deposition  followed  the  erupt'on  of  lava.  The  minerals  deposited 
and  the  manner  of  their  deposition  are  such  as  in  the  more  northerly  quick- 
silver districts  were  induced  by  volcanic  springs.  Though  there  are  now 
no  indubitable  remnants  of  the  volcanic  activity  Avhich  certainly  prevailed 
here  since  the  beginning  of  the  Pliocene,  the  analogies  of  the  deposit, 
together  with  the  presence  of  lava  of  approximately  the  same  age  as  the 
ore,  make  any  theory  of  deposition  excepting  from  hot  sulphur  springs 
improbable.  The  source  of  the  ore  will  be  discussed  in  a  future  chapter. 

General  fissure  system. — The  rliyolite  dike,  of  course,  represents  a  deep  fis- 
sure. The  length  of  this  dike  shown  on  the  map  is  about  twenty  thousand 
feet,  but  I  have  followed  it  beyond  the  map  limit  for  a  considerable  dis- 
tance. The  presence  and  the  character  of  the  range  also  indicate  the 
existence  of  an  axis  of  disturbance,  though  its  direction  is  mpre  or  less  ob- 
scured by  irregularities  in  metamorphism  and  erosion.  There  can,  further, 
be  no  doubt  from  the  foregoing  description  that  the  cinnabar  deposits 
occur  along  fissures.  The  question  arises,  what  connection  exists  between 
the  fissures  upon  which  the  various  deposits  are  found  ?  It  is  hardly  pos- 
sible to  consider  the  relative  position  of  the  Guadalupe,  San  Mateo,  San 
Antonio,  Enriquita,  Providentia,  America,  and  Washington  without  coming 
to  the  conclusion  that  they  form  a  substantially  continuous  series  of  de- 
posits. If  the  strike  of  the  Guadalupe,  the  Enriquita,  and  the  Washington 
be  taken  into  account  this  impression  is  strengthened,  for  it  is  easy  to  draw 
a  continuous  line  through  the  deposits  which  will  coincide  with  the  strike  of 
each.  This  series  leaves  out  the  New  Almaden  and  the  Cora  Blanca.  The 
deep  fissures  of  the  New  Almaden  to  the  northeast  of  the  Randol  shaft  are 
nearly  straight,  approximately  vertical,  and  strongly  marked  by  slicken- 
sides,  clays,  and  other  evidences  of  motion.  They  must  be  very  profound 
and  persistent  fissures.  They  strike  nearly  for  the  workings  of  the  Amer- 
ica. The  fissures  on  the  lower  levels  have  been  followed  for  about  one 
thousand  feet  and  to  about  twenty-two  hundred  feet  in  a  horizontal  direc- 
tion from  the  America.  I  cannot  believe  that  these  strong  fissures  can  die 
out  within  this  distance  or  that  they  can  greatly  change  in  general  direc- 
tion. They  might  possibly  be  replaced  by  other  fissures  near  to  them  and 
parallel  with  them,  the  two  sets  being  connected  by  more  or  less  indistinct 


GENERAL  FISSURE  SYSTEM. 


329 


cross-courses,  but  this  would  be  substantial  continuity.  If  I  am  right,  the 
New  Almaden  deep  fissures  connect  with  the  ore-bearing  fissures  south  of 
the  ridge  and  cross  the  ridge  near  the  America.  Considering  the  amount  of 
disturbance  on  the  New  Almaden  fissures~tliey  would  seem  to  represent  the 
main  line  of  fracture,  and  in  that  case  the  crack  leading  to  the  Washington  is 
in  the  nature  of  a  cross-course.  The  apparent  strike  of  the  America  accords 
with  this  view,  which  is  strengthened  by  the  relations  to  the  dike  to  be  men- 
tioned presently.  As  for  the  Cora  Blanca,  the  fact  that  the  deposit  is  largely 
bedded  or  that  it  follows  the  stratification  complicates  its  relations,  for  its 
strike  is  very  likely  to  differ  considerably  from  that  which  it  would  have  if  the 
structure  of  the  country  had  not  presented  a  local  line  of  weakness.  It  may 
be  that  this  mine  is  on  a  cross-course  nearly  parallel  to  the  Washington,  but 
the  evidence  is  hardly  sufficient  to  justify  speculation.  The  following  sketch 
shows  the  approximate  positions  of  the  several  deposits  of  the  ridge  and  of 
the  dike.  The  strike  of  the  main  deposits  is  also  indicated  and  a  fine  line 
is  drawn  through  all  except  the  Cora  Blanca.  The  upper  portion  of  the 
south  fissure  oflthe  New  Almaden  is  not  represented  on  the  sketch  for  lack 
of  data.  The  Iroppings  of  this  fissure  probably  curve  rapidly  toward  those 
of  its  northern1-  companion,  but  the  soil  and  artificial  disturbances  obscure 
the  line  (Fig/ 13). 


FIG.  13.  R,  deep  fissures  of  .the  New  Almaden  near  the  Eandol  shaft;    W,  Washington  deposit:    A,  America;  S,  Cora 
Blanca;  P,  Proviilentia ;  E,  Knriquita;  SA,  San  Antonio;  M,  San  Mateo;  a,  GuaUalupe;   dd  rhyolite  dike. 

The  straightness  and  persistence  of  the  dike  seem  to  show  that  its  crop- 
pings  have  the  same  strike  as  the  main  fissure  through  which  it  reached 


330  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  surface.  I  have  shown  that  the  deposits  were  probably  induced  by 
volcanic  activity  following  the  eruption  of  this  lava,  so  that  a  not  very 
remote  connection  exists  between  the  ore-bearing  fissures  and  that  marked 
by  rhyolite.  At  the  time  of  the  lava  eruption  the  present  range  of  hills 
existed  much  as  it  does  to-day.  Consequently  the  course  of  a  fissure  tend- 
ing to  assume  a  strike  nearly  parallel  to  that  of  the  dike  and  which  was 
formed  near  the  range  of  the  hills  would  be  affected  by  their  presence. 
The  hills  would  act  as -a  mass  of  considerable  rigidity  and  would  tend  to 
deflect  such  a  fissure,  but  if  at  any  point  this  tendency  were  overcome  the 
fissure  would  return  more  or  less  closely  to  the  direction  of  the  dike.  Now, 
near  the  Guadalupe  the  line  connecting  the  deposits  is  almost  exactly  par- 
allel to  the  dike ;  as  the  ridge  curves  away  from  the  dike  the  line  of  de- 
posits follows  the  high  ground.  After  the  angle  between  the  ridge  and  the 
dike  becomes  large  the  line  of  fissure  seems  to  me  to  cross  the  high  land 
and  to  approach  the  dike  again  in  the  New  Almaden  ground  at  an  angle  of 
about  30°.  In  crossing  the  ridge  a  branch  fissure  seems  to  have  been 
formed  leading  to  the  Washington. 

I  cannot,  of  course,  pretend  to  have  demonstrated  the  above  explana- 
tion of  the  relations  of  the  deposits.  For  this  the  exposures  are  insufficient. 
I  offer  it,  however,  as  a  working  hypothesis  which  possesses  considerable 
probability  and  may  serve  as  the  basis  for  a  more  exact  theory  to  be  elab- 
orated by  the  engineers  in  charge  of  the  properties.  It  is  probably  needless 
to  remark  that  if  the  hypothesis  set  forth  above  be  true  it  shows  where  ore 
is  to  be  sought,  but  ore  will  be  found  only  at  certain  favored  points  or  in 
certain  channels  at  or  near  the  fissures.  If  the  Washington  fissure  actually 
meets  that  connecting  the  New  Almaden  and  the  America,  great  disturbances 
must  have  taken  place  at  the  junction  and  some  ore  will  probably  be  found 
there. 


CHAPTER  XT. 

DESCRIPTIVE  GEOLOGY  OF  THE  STEAMBOAT  SPRINGS 

DISTRICT. 

[Atlas   Sheet   XIV.] 

character  of  the  district. —  Steamboat  Springs  lies  between  the  Sierra  Nevada 
and  the  Virginia  Range,  at  the  western  edge  of  the  Great  Basin.  The 
forests  and  snows  of  the  great  Sierra  ai-e  in  sight  a  few  miles  away,  but  in 
the  neighborhood  of  the  springs  only  sage  brush  grows  without  irrigation. 
The  soil  in  the  lowlands,  however,  is  fertile,  and  sufficient  water  is  avail- 
able to  bring  a  considerable  surface  under  cultivation.  The  hills  are  for 
the  most  part  bare  rock,  as  geologists  love  to  see  them.  Many  of  the 
exposures  are  whitened  or  reddened  by  solfataric  action,  and  on  cool  days 
tall  columns  of  steam  rise  from  the  numerous  hot  springs,  giving  the  local- 
ity a  weird  appearance.  Steamboat  Springs  is -only  six  miles  from  the 
Comstock  lode  and  lies  at  the  northwest  base  of  Mt.  Davidson,  on  the 
eastern  flank  of  which  is  the  great  silver  vein.  The  intervening  space  is  for 
the  most  part  covered  with  lavas,  one  of  the  sheets  of  which  seems  to  be 
continuous  for  the  entire  distance.  All  the  rocks  which  occur  at  Steam- 
boat are  also  found  in  the  immediate  neighborhood  of  the  Comstock,  and 
the  fissures  of  the  two  localities  are  approximately  parallel  cracks,  with 
many  points  of  resemblance.  Steamboat  affords  fine  opportunities  for  the 
investigation  of  massive  rocks,  and  the  occurrences  here  serve  to  throw 
much  additional  light  on  the  rocks  of  the  Washoe  district,  described  by  me 
in  Vol.  Ill  of  this  series.  The  proximity  of  the  areas  permitted  me  to 
make  direct  comparisons  during  the  present  investigation.  The  spring 

331 


332  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

deposits  also  have  long  been  known  to  be  of  extraordinary  interest,  because 
they  contain  metallic  compounds,  including  cinnabar  and  gold.  So  much 
cinnabar  is  found  here  in  areas  still  emitting  steam  and  sulphur  gases  that 
mining  operations  were  undertaken  some  years  since  and  a  furnace  was  run 
for  a  time  on  the  ore.  That  quicksilver  was  produced  is  certain,  though 
I  was  unable  to  ascertain  how  many  flasks.  A  considerable  amount  of  ore 
is  in  sight,  and  there  is  no  apparent  reason  to  doubt  that  were  the  price  of 
the  metal  to  rise  to  a  dollar  a  pound  the  deposit  might  be  worked  at  some 
profit. 

Here,  if  anywhere,  the  question  of  the  mode  of  genesis  of  cinnabar 
deposits  can  be  settled,  and  the  study  of  the  locality  was  undertaken  on 
that  account.  The  results  of  this  study  and  of  laboratory  experiments 
suggested  by  it  appear  in  this  and  succeeding  chapters. 

Granite — The  Hthological  character  of  the  massive  rocks  of  Steamboat 
has  been  described  in  Chapter  IV,  and  the  details  do  not  require  repetition 
here  excepting  in  reference  to  the  distribution  of  the  rocks  and  their  rela- 
tions to  field  habit,  The  granite,  which  is  exposed  to  a  large  extent,  mani- 
festly underlies  the  whole  region.  In  external  appearance  it  is  thoroughly 
typical,  and  no  geologist  would  doubt  for  a  moment  how  to  classify  it.  It 
is  unstratified,  much  fissured,  weathers  irregularly,  and  sometimes  crumbles 
to  a  coarse  gravel,  as  granites  often  do.  Some  of  it  is  coarse,  and  it  dis- 
plays considerable  irregularities  in  texture  and  mineralogical  composition, 
as  if  it  had  never  been  thoroughly  fluid.  Plagioclase  is  occasionally  visible 
with  the  naked  eye,  but  the  predominant  feldspar  seems  to  be  orthoclase. 
Under  the  microscope  this  granite  appears  less  typical,  inasmuch  as  the 
quantity  of  triclinic  feldspar  seems  in  the  slides  unusually  large,  and  one 
might  well  doubt  whether  to  class  some  of  the  rock  as  orthoclastic  or  pla- 
gioclastic.  This  is  one  of  the  cases  in  which  the  appearance  is  less  truthful 
under  the  microscope  than  to  the  unaided  vision,  and  this  is  doubtless  due 
to  the  fact  that  the  plagioclase  is  recognized  by  positive  characters  between 
crossed  nicols,  while  the  presence  of  orthoclase  is  evinced  chiefly  by  the 
absence  of  polysynthetic  structure.  Separation  by  specific  gravity  shows 
that  the  more  plagioclastic  specimens  of  the  rock  contain  about  as  much 
orthoclase  as  plagioclase.  The  granite  of  Steamboat  Springs  is  substan- 


SEDIMENTARY  KOCKS  AT  STEAMBOAT.  333 

tially  similar  to  that  which  appears  near  the  southern  end  of  the  Comstock 
Lode.  The  superficial  exposure  there  is  very  small,  but  the  rock  extends 
into  the  workings  of  the  mines  at  American  Flat.  Similar  granite  is  found 
near  Washoe  Lake,  some  miles  south  of  Steamboat,  and  large  exposures  of 
it  exist  between  these  points  and  Lake  Tahoe,  in  the  Sierra. 

The  granite  is  intersected  by  distinct  dikes  of  granite  porphyry.  So 
far  as  observed  these  dikes  do  not  penetrate  the  sedimentary  rocks  and  are 
probably  older  than  the  beds. 

The  metamorphic  scries. —  Upon  the  granite  lies  a  considerable  area  of  sedi- 
ments, which  are  in  part  very  highly  metamorphosed  and  in  part  but  little 
altered.  These  beds  are  usually  nearly  vertical  and  strike  with  the  trend 
of  the  Sierra.  Attempts  to  make  two  series  of  them  failed  and  only  resulted 
in  showing  that  the  metamorphism  was  partial  and  irregular.  The  highly 
altered  portions  considerably  resemble  Archaean  schists,  but  the  partial 
character  of  the  metamorphism  seems  to  forbid  their  reference  to  a  Pre- 
Cambrian  age.  They  are  certainly  Pre-Tertiary,  for  there  are  Tertiary 
strata  within  a  few  miles  both  to  the  north  and  to  the  south  which  are  far 
less  disturbed  and  not  at  all  metamorphosed.  The  only  other  sedimentary 
rocks  known  to  exist  near  the  eastern  edge  of  the  Great  Basin  in  this  lati- 
tude are  those  determined  to  be  Jura-Trias  by  the  paleontologists  who  dis- 
cussed the  fossils  collected  by  the  geologists  of  the  Geological  Exploration  of 
the  Fortieth  Parallel.  Dr.  White,  on  reviewing  the  evidence  on  which  the 
assignment  was  made,  thinks  it  insufficient  to  justify  any  conclusion  more 
definite  than  that  the  beds  in  question  are  Mesozoic.  The  descriptions  of 
these  Mesozoic  rocks  accord  very  well  with  the  strata  found  at  Steamboat. 
Their  metamorphism  is  perhaps  an  evidence  that  they  are  not  younger  than 
the  Neocomian,  for  no  more  recent  alteration  of  any  such  intensity  is  known 
to  have  taken  place  later  than  the  Post-Neocomian  upheaval  so  often  re- 
ferred to  in  this  volume.  The  upheaval  is  the  same  as  that  called  the  Post- 
Jurassic  by  Professor  Whitney,  and  its  existence  was  no  doubt  given  due 
weight  by  the  geologists  of  the  fortieth  parallel  when  they  referred  the 
Mesozoic  beds  of  Nevada  to  the  Jura-Trias.  As  this  region  is  separated 
from  the  gold  belt  by  a  great  range  of  mountains,  however,  it  is  not  impos- 
sible that  its  metamorphism  may  have  been  subsequent  to  and  independent 


334  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

of  that  of  California,  though  no  known  fact  lends  this  supposition  proba- 
bility. A  prolonged,  but  wholly  unsuccessful  search  was  made  for  fossils, 
which  are  also  very  rare  in  the  other  Mesozoic  rocks  of  Nevada. 

A  portion  of  these  rocks  are  conglomerates.  Among  the  pebbles  of 
these  conglomerates  are  some  of  diabase,  identical  with  the  porphyritic 
diabase  which  forms  the  hanging  wall  of  the  Comstock  lode.  There  can  be 
little  doubt  that  these  pebbles  formed  a  portion  of  masses  which  were  erupted 
simultaneously  with  that  at  Virginia,  and  it  is  possible  that  they  came  from 
that  very  mass,  though  this  is  not  certain.  I  did  not  succeed  in  finding  peb- 
bles of  the  still  older  diorite  of  Mt.  Davidson,  which  may  perhaps  have  been 
buried  under  the  diabase  at  the  time  when  the  conglomerates  were  laid 
down.  The  bearings  of  the  occurrence  of  diabase  pebbles  at  Steamboat 
on  the  geology  of  Washoe  I  have  enlarged  upon  in  another  publication.1 

Earlier  hornblende-andesite Tl>6    oldest    of     tll6    laVaS    of    tll6    district    is    llOm- 

blende-andesite.  It  overlies  the  metamorphic  beds  in  part  and  is  distinctly 
more  recent  than  the  date  of  their  upheaval.  All  this  lava  is  very  compact  and 
of  a  bluish  tint,  but  it  is  divisible  into  three  varieties:  one  extremely  fine- 
grained and  often  of  a  slaty  texture ;  one  a  comparatively  coarse-grained, 
porphyritic  rock ;  the  last  glassy.  Of  these  the  first  is  most  common.  It  is 
also  found  near  the  Ophir  grade  at  Virginia,  and  the  two  occurrences  are 
indistinguishably  similar.  The  coarse-grained,  somewhat  grayish  porphyry 
is  best  represented  at  Steamboat,  near  the  eastern  edge  of  the  map.  At 
Virginia  this  modification  is  perhaps  the  commonest.  The  glassy  variety, 
associated  with  the  others,  is  found  at  the  western  edge  of  the  map  of  Steam- 
boat Springs.  In  this  area  there  also  occurs  a  very  small  amount  of  a 
pyroxenic  andesite  which,  after  careful  study,  seems  to  me  to  represent  a 
strictly  local  variation  in  mineralogical  composition  and  to  pass  over  into 
the  hornblende  rock  by  transitions.  The  fact  that  this  andesite  overlies  the 
metamorphics  seems  to  indicate  that  it  is  later  than  the  early  Cretaceous. 
The  existence  of  glassy  modifications  forming  a  portion  of  the  areas  is  evi- 
dence that  it  is  much  later  than  the  Cretaceous.  Indeed  it  is  hard  to  under- 
stand how  the  glass  can  have  failed  to  be  removed  if  this  andesite  is  older 
than  the  Pliocene. 

1  The  Washoe  rocks  :  Bull.  California  Acarl.  Sei.  No.  !i,  vol.'J,  1887,  p.  93. 


ASPEKITES  AT  STEAMBOAT.  335 

Later  andesites. — More  recent  than  the  hornbleiide-andesites  described 
above  are  other  andesitic  rocks.  These  are  divisible  mineralogically  into 
three  varieties,  and  are  so  laid  down  upon  the  map.  They  appear,  how- 
ever, to  have  been  ejected  almost  simultaneously.  They  are  all  so  recent 
that  extremely  little  erosion  has  taken  place  and  only  a  few  depressions  arc 
marked  by  water- courses.  The  difference  in  this  respect  between  the  areas 
of  later  andesites  and  the  metamorphic  areas  is  readily  seen  from  the  map 
where  the  amount  of  sculpturing  corresponds  to  the  geological  colors. 

All  the  later  andesites  are  rough,  soft  rocks,  in  which  the  feldspars  are 
much  cracked.  Some  of  them  are  laminated,  the  beds  averaging  perhaps 
an  inch  and  a  half  in  thickness,  and  this  modification  is  physically  indis- 
tinguishable from  similar  occurrences  at  Clear  Lake.  One  variety  of  these 
rocks  is  highly  pyroxenic ;  a  second  is  hornblendic,  though  not  free  from 
pyroxene,  and  sometimes  contains  mica,  while  often  lacking  this  constituent. 
Between  the  pyroxenic  and  hornblendic  rocks  are  transitions  of  the1  most 
unmistakable  kind,  which  I  have  designated  by  a  separate  color  and  have 
entitled  for  the  purposes  of  this  one  map  "  transition  andesite."  In  thesa 
areas  the  composition  of  the  rock  is  curiously  variable.  Thus,  in  a  little 
triangular  patch  nearly  south  of  the  mines  and  embracing  considerably  less 
than  two  acres,  specimens  can  be  collected  which  in  the  office  might  well  be 
supposed  to  represent  three  distinct  species:  one  a  pyroxene-andesite,  one  a 
simple  hornbleude-andesite  without  mica,  and  the  third  a  micaceous  liorn- 
blende-andesite.  But  the  whole  area  is  thoroughly  exposed  and  certainly 
represents  only  a  simple  eruption.  The  different  varieties  of  rock  were 
found  here  and  elsewhere  within  a  few  inches  of  one  another  on  the  same 
blocks  of  lava,  Such  occurrences  show  how  hopeless  is  the  attempt  to 
reconstruct  the  geology  of  an  eruptive  district  from  collections  alone. 

The  area  colored  as  later  hornblende-andesite  is  covered  with  rock 
almost  indistinguishable  from  the  later  hornblende-andesite  near  the  Corn- 
stock  ;  indeed,  a  very  large  proportion  of  the  region  intervening  between 
the  two  districts  is  occupied  by  this  rock  and  the  lava  field  seems  to  be 
continuous  from  the  northern  end  of  the  Comstock  area  to  the  eastern  edge 
of  the  Steamboat  Springs  map.  In  botli  neighborhoods  the  quantity  of 
mica  is  variable,  but  near  Steamboat  it  is  exceedingly  capricious.  Mica  is 


336  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sometimes  present  in  most  unusual  quantities,  forming  a  large  percentage  of 
the  entire  mass,  and  such  flows  appear  to  have  been  the  latest  of  all.  Else- 
where the  rock  is  scantily  supplied  with  mica  and  over  considerable  areas 
the  most  diligent  search  failed  to  reveal  a  single  flake. 

The  non-micaceous  portions  of  the  later  hornblende-andesites  are  dis- 
tinguishable from  the  pyroxene -andesite  only  by  the  relative  abundance  of 
the  bisilicates,  texture  and  habitus  being  identical  and  both  of  them  trachytic. 
The  hornblendic  and  the  pyroxenic  modifications  of  this  rock  are  in  con- 
tact at  the  eastern  portion  of  the  map.  Neither  is  eroded  to  any  considera- 
ble extent,  though  both  areas  are  more  or  less  covered  with  loose  fragments. 
I  was  unable  to  make  sure  whether  the  eruptions  had  been  actually  simul- 
taneous or  not.  On  the  whole,  the  pyroxenic  rock  seemed  a  little  earlier 
than  the  hornblendic  lava.  On  comparing  the  occurrences  here  with  those 
at  Virginia  I  found  that  transitions  occurred  at  the  latter  locality  also,  which 
I  had  overlooked  when  I  mapped  the  geology  of  that  region.  The  transi- 
tion rocks  in  the  Washoe  district  occur  along  the  ridge  of  which  Mt.  Kate 
forms  a  part  and  near  that  peak,  and  are  present  in  small  quantities  only.1 
At  Virginia  the  pyroxenic  portion  of  the  later  andesites  is  older  than  that 
which  carries  mica.  On  the  other  hand,  Mr.  Lindgren  found  near  Mono 
Lake  flows  of  pyroxenic  andesites,  entirely  similar  to  that  of  Steamboat, 
overlying  micaceous,  hornblendic  andesites.  The  order  of  succession  is  thus 
not  a  fixed  one.  At  Steamboat  the  two  are  very  nearly  and  perhaps  abso- 
lutely contemporaneous.  Both  of  them  are  later  than  the  earlier  dense 
hornblende-andesite  and  have  overflowed  it.  The  area  of  the  older  ande- 
sites at  the  east  of  the  map  is  also  intersected  by  dikes  of  the  later  rocks. 
These  dikes  are  in  part  micaceous  and  in  part  free  from  mica.  Those  por- 
tions of  them  which  carry  no  mica  are  sometimes  highly  charged  with  horn- 
blende and  sometimes  carry  comparatively  large  quantities  of  pyroxene. 

1  Tho  occurrence  of  these  transitions  shows  that  the  pyroxeue-audesito  of  the  Mt.  Kato  Range  im- 
mediately preceded  the  later  horublende-audesite  adjoining  it.  Tho  pyroxene-andesito  of  the  Washoe 
district  (laid  down  on  the  map  as  augite-audesite)  is  divisible  into  two  eruptions,  one  much  older  than 
the  other,  though  without  any  intervening  outburst.  Tho  Washoe  district  contains  three  pyroxenic 
rocks  of  different  ages:  diabase,  which  was  followed  by  a  hornblcnde-amU-site,  and  two  successive 
outflo  ws  of  pyrox^ne-audcsite,  both  later  thau  this  earlier  horn  blendc-andesi  to.  The  pyroxene-andesites 
were  again  followed  by  later  hornblende-andesite.  Dr.  Whitman  Cross  pointed  out  the  prevalence  of 
hypersthone  in  audesito  after  iny  discussion  of  the  lithology  of  Washacs  was  completed.  Compare  my 
paper,  "  Washoe  rocks,"  cited  above. 


[UNIVERSITY] 

AU..ITIB  AT  •»»*&.££& 

They  are  all  of  the  trachytic  type.  Similar  rocks  occur  aBImdantly  in  the 
surrounding  region.  Special  mention  may  be  made  of  the  Hufaker  Butte, 
which  is  an  isolated  volcanic  mass  about  four  miles  north  of  Steamboat,  in 
the  valley.  This  seems  clearly  to  represent  a  single  eruption  or  a  series  of 
eruptions  embraced  within  a  short  interval  of  time.  The  rock  is  all  tra- 
chytic, in  part  highly  micaceous  and  in  part  free  from  mica. 

While  it  is  quite  possible  to  distinguish  varieties  among  these  later  an- 
desites,  they  pass  over  into  one  another  in  such  a  manner  as  to  indicate  that 
they  form  a  natural  group.  The  distinctions  are,  at  least  near  Steamboat 
Springs,  of  little  geological  importance.  As  is  pointed  out  in  Chapter  IV, 
similar  rocks  occur  at  Mt.  Shasta  and  from  Clear  Lake  to  the  Bay  of  San 
Francisco,  Imt  those  of  the  latter  area  are  remarkable  because  they  usually 
contain  mica  and  pyroxene,  but  no  hornblende.  All  these  andesites  seem 
to  be  more  recent  than  the  close  of  the  Pliocene  and  all  have  a  similar 
physical  character.  Some  contain  pyroxene  with  a  very  little  hornblende; 
some,  pyroxene  and  mica,  but  no  hornblende;  some,  hornblende  with  a  little 
pyroxene  and  no  mica;  some,  much  mica,  a  little  hornblende,  and  a  trace 
of  pyroxene.  Every  possible  combination  of  these  ferromagnesian  silicates 
excepting  those  altogether  excluding  pyroxene  is  represented ;  there  is  no 
known  difference  in  mode  of  occurrence  and  the  order  of  succession  is 
variable.  This  group  of  rocks  is  the  same  which,  before  the  reference  of 
lavas  to  the  microscope  became  habitual,  were -regarded  as  trachytes.  The 
name  is  indefensible,  for  the  rocks  are  plagioclastic ;  but  the  thing  to  which 
it  was  given  is  a  geological  entity.  I  have  therefore  proposed  for  this  nat- 
ural group  of  rocks  the  name  aspcritcs,  which  is  etymologically  an  equiva- 
lent of  trachyte,  but  of  Latin  origin. 

Basalt. — The  basalt  of  Steamboat  is  in  no  respect  remarkable.  Though 
it  covers  a  considerable  area,  the  amount  of  the  rock  is  by  no  means  great, 
for  it  is  evident  from  some  exposures  that  the  sheet  is  only  a  few  yards  in 
thickness.  1  Kmbtless,  however,  the  depth  of  the  lava  is  variable.  Basaltic 
breccias  form  a  portion  of  the  mass.  The  basalt  eruption  antedates  the 
deposition  of  ore,  at  least  in  part;  for  where  it  adjoins  the  mine  it  is  sol- 
fatarically  decomposed  and  cinnabar  has  been  deposited  in  crevices  in  the 
lava.  The  spring  deposits,  including  the  cinnabar,  have  formed  close  to 

MON  XIII 22 


338  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  edge  of  the  basalt,  and  I  can  see  no  reason  to  doubt  that  they  result 
from  the  volcanic  action  of  which  the  lava  eruption  was  one  manifestation. 

The  springs. — The  present  vents  of  the  springs  lie  along  a  series  of  fissures 
about  a  mile  in  length,  shown  on  the  map  nearly  parallel  to  the  railroad. 
These  cracks  have  formed  in  a  mass  of  sinter  deposited  from  earlier  vents  and 
are  in  part  choked  up  by  detritus,  in  part  covered  by  recent  deposits,  but 
they  are  nevertheless  traceable  for  long  distances.  The  vents  in  many  cases 
retain  their  fissure  character  and  the  water  may  be  seen  and  heard  boiling 
in  openings,  evidently  of  great  depth,  from  an  inch  to  two  feet  in  width  and 
many  yards  in  length.  At  other  points  the  cracks  are  closed,  with  the  ex- 
ception of  pipe-like  openings,  through  which  the  water  reaches  the  surface. 
At  vents  of  the  latter  class  there  often  form  smooth  mounds  of  Winter,  from 
the  summit  of  which  the  water  escapes  continuously  or  fitfully.  Some  of 
the  springs  have  a  true  geyser  character,  though  on  a  very  small  scale, 
alternately  disappearing  from  their  basins  and  returning  to  them  with  noise 
and  agitation  at  short  intervals  of  time.  It  is  said  by  the  inhabitants  that 
in  some  seasons  the  water  returns  to  certain  of  the  basins  with  sufficient 
violence  to  be  thrown  several  feet  into  the  air,  but  during  my  visits  the 
maximum  action  did  not  exceed  a  plentiful  overflow. 

It  is  very  clear  that  these  springs  are  short-lived.  In  the  most  active 
area  they  are  to  bj  found  in  every  approach  to  extinction.  Some  have 
completely  covered  their  own  vents  with  sinter,  though  when  the  crust  is 
broken  hot  wator  is  still  found  below,  while  other  mounds  and  cracks  are 
completely  cold.  Some  very  active  vents  are  also  manifestly  extremely 
recent  and  have  only  lately  begun  to  form  new  deposits.  The  extinction 
and  subsequent  formation  of  springs  has  certainly  been  in  progress  for  a 
long  time  and  the  accumulation  of  sinter  is  large.  The  upper  line  of  vents 
is  about  one  hundred  feet  above  the  railroad,  which  runs  along  the  base 
of  the  mass  of  sinter.  The  ground  beneath  the  sinter,  however,  evidently 
slopes  outward  from  the  hills,  and  the  maximum  thickness  of  the  deposits  is 
probably  about  fifty  feet.  Active  springs  formerly  existed  at  many  other 
points.  The  map  extends  eastward  to  the  foot  of  the  Virginia  Range.  The 
rocks  of  this  range  a  little  farther  eastward  are  greatly  decomposed,  apparent- 
ly by  solfataric  action.  There  is  also  on  the  map  east  of  the  railroad  one 


STEAMBOAT  SPRINGS.  339 

small  area  of  sinter  in  which  there  is  now  no  evidence  of  activity.  Much 
of  the  main  area  of  sinter  is  likewise  cold  and  dry,  but  some  three  thousand 
feet  due  west  of  the  active  group  of  fissures  is  a  second  group,  now  nearly 
extinct,  of  which  only  one  is  shown  on  the  map.  From  this  small  quantities 
of  steam  and  other  gases  still  escape  at  a  few  points.  At  the  mine  only 
small  quantities  of  sinter  exist  and  the  fissures  are  not  superficially  defined 
as  in  the  areas  just  mentioned,  though  it  is  clear  that  the  lines  of  vent  ex- 
tended in  a  direction  nearly  north  and  south.  In  some  of  the  excavations 
the  ground  is  moist  and  still  hot  enough  to  be  painful  to  the  touch.  Gase-i, 
too,  still  escape,  but  no  water  flows.  The  entire  area  of  sinter  and  decom- 
posed granite  north  and  west  of  the  basalt  area  is  continuous  and  manifestly 
has  a  common  origin.  There  can  of  course  be  no  question  that  the  thermal 
action  of  this  locality  is  volcanic.  The  area  of  thermal  activity  is  at  the 
foot  of  a  stream  of  comparatively  recent  basalt,  which  was  the  last  rock 
ejected.  The  relations  thus  point  very  clearly  to  an  immediate  connection 
between  the  basalt  eruption  and  hot  springs. 

In  discussing  the  solfatarism  of  the  Washoe  district  I  inferred  that  it 
was  probably  of  later  date  than  the  eruption  of  later  hornblende-ande- 
site,  while  of  its  time-relations  to  the  basalt  eruption  there  was  no  means 
of  judging.1  I  was  not  then  aware  of  the  evidence  that  the  activity  at 
Steamboat  was  directly  referable  to  the  eruption  of  basalt.  The  thermal 
action  on  the  Comstock  has  advanced  somewhat  farther  towards  extinction 
than  that  at  Steamboat;  for,  while  the  water  on  the  3,000-foot  level  of  the 
Comstock  is  charged  with  carbonic  and  sulphydric  acids  and  has  a  tempera- 
ture of  76.7°  C.,  most  of  the  vents  at  the  surface  at  Steamboat  show  still 
higher  temperatures  and  the  water  at  a  distance  of  half  a  mile  below  must 
be  greatly  superheated.  Nevertheless  the  thermal  action  in  each  of  the 
districts  must  be  of  approximately  the  same  age,  as  are  also  the  basalt  erup- 
tions of  tin;  two  areas;  and  the  fact  that  the  origin  of  the  spring  in  the  one 
cast;  is  directly  traceable  to  the  eruption  of  basalt  makes  it  extremely  prob- 
able that  in  the  other  also  the  basalt  eruption  gave  rise  to  the  thermal  ac- 
tivity. The  relations  of  the  lava  to  the  springs  at  Steamboat  are  strikingly 

1  Geology  of  the  Comstock  Lode,  p.  207. 


340  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

similar  to  those  studied  by  Dr.  Hector  near  Lake  Omapere,  in  New  Zea- 
land, where,  too,  the  sinter  contains  cinnabar.     (See  page  50.) 

Diversities. — The  effects  produced  by  the  action  of  the  heated  waters  and 
of  the  gases  accompanying  them  in  the  various  portions  of  the  affected  area 
differ  very  materially  and  in  an  interesting  manner.  The  heavy  masses  of 
sinter  near  the  railroad  are  to  a  considerable  extent  composed  of  carbonates 
and  all  effervesce  with  acids.  Much  of  the  mass  is  silica,  however,  in  part 
crystalline  and  in  part  amorphous.  The  material  is  deposited  in  layers  or 
bands,  partly  lining  crevices  and  partly  covering  the  adjacent  country  in 
more  or  less  nearly  horizontal  sheets.  The  linings  of  the  crevices  have  a 
ribbon  structure  precisely  such  as  is  found  in  veins  and  composed  of  sub- 
stantially the  materials  most  common  in  veins,  excepting  indeed  the  hy- 
drated  silica.  In  the  northwestern  part  of  the  area  carbonates  occur  only 
in  small  quantities.  The  deposits  here  are  for  the  most  part  chalcedony, 
which  also  exhibits  ribbon  structure.  In  the  neighborhood  of  the  mine 
workings  only  small  quantities  of  silica  and  carbonates  have  been  deposited. 
Here,  indeed,  the  quantity  of  material  removed  by  the  spring  waters  is 
greatly  in  excess  of  the  deposits  which  they  have  formed.  In  the  southern 
part  of  the  ground,  where  mining  has  been  carried  on,  an  actual  basin  has 
been  formed,  with  a  low  rim  to  the  north,  which,  however,  is  not  sufficiently 
high  to  be  exhibited  by  the  20-foot  contour  lines.  This  basin,  from  which 
there  is  no  drainage,  is  not  artificial,  and  appears  beyond  question  to  have 
formed  in  consequence  of  the  collapse  of  the  decomposed  granite,  yet  it 
contains  not  only  cinnabar,  but  a  thin  layer  of  sinter  composed  of  carbonates 
and  silica 

There  is  no  reason  to  suppose  that  the  general  character  of  the  fluids 
and  gases  which  have  been  active  in  the  various  portions  of  this  area  dif- 
fered qualitatively  ;  on  the  contrary,  the  entire  character  of  the  deposits  and 
the  distribution  of  decomposed  granite  indicate  that  the  qualitative  com- 
position was  the  same.  Variations  in  the  quantitative  composition  of  the 
waters  thus  seems  to  have  been  sufficient  to  bring  about  either  the  deposi- 
tion of  large  masses  of  material  or  an  actual  subsidence  of  the  surface. 
This  important  inference  maysaom  doubtful  when  drawn  from  this  locality 
alone;  for,  though  there  is  no  indication  of  a  qualitative  difference  in  the 


SINTERS  AT  STEAMBOAT.  341 

waters,  the  proof  that  the  water  which  undermined  the  basin  south  of  the 
furnaces  was  similar  to  that  now  issuing  near  the  railway  is  negative.  At 
Sulphur  Bank,  however,  we  have  springs  of  similar  qualitative  composi- 
tion which  are  not  depositing  sinter  to  any  extent  and  which  are  actually 
removing  material  by  their  solvent  action.  The  difference  at  the  two 
localities  appears  to  depend  largely  upon  the  quantity  of  sulphuric  acid 
generated.  At  Steamboat,  also,  the  depressed  basin  contains  sulphates, 
which  have  been  formed  by  the  action  of  sulphuric  acid  on  the  rocks, 
and  I  can  see  no  reason  to  doubt  that  the  quantity  of  sulphuric  acid 
generated  has  determined  deposition  of  sinter  or  removal  of  constituents 
of  the  rocks. 

The  silica  of  the  sinters. —  As  has  been  stated,  one  portion  of  the  sinter  area 
consists  almost  solely  of  a  flinty  or  chalcedonic  mass.  This  is  by  no  means 
ancient,  for  scalding  steam  still  issues  at  one  point,  nor  does  it  show  any  signs 
of  erosion.  Under  the  microscope  the  sinter  is  found  to  be  composed  of  ordi- 
nary  quartz  crystals  and  fibrous,  crystalline  silica.  No  opal  was  detected 
with  certainty  by  the  microscope.  This  rock  is  almost  absolutely  identical 
with  some  of  the  chalcedonic  specimens  from  Knoxville,  which  contain,  in 
addition,  cinnabar.  The  sinters  from  the  springs  now  most  active  are  finer 
grained  than  that  just  described.  They  are  composed  of  silica  and  carbon- 
ates. The  silica  is  certainly  in  part  crystalline  and  does  not  remain  dark 
between  crossed  nicols. 

To  obtain  further  information  about  the  existence  of  opal,  water  deter- 
minations were  made  of  three  specimens,  care  being  taken  to  separate  the 
water  from  other  volatile  constituents.  One  of  the  specimens  was  a  rnilky- 
white,  compact  rock  with  dull  luster;  a  second  was  a  very  dark  slate-col- 
ored rock  with  a  resinous  luster;  and  the  third,  a  pure-white  sinter,  earthy 
and  friable  in  part.  The  water  absorbed  in  a  calcium  chloride  tube  was 
in  the  order  of  the  descriptions  0.72,  3.77,  and  0.67  per  cent.  These  ex- 
periments show  that  hydrous  silica  was  present  in  three  specimens  and 
that  they  were  true  chalcedonies,  if  by  that  term  is  understood  a  mixture 
of  crystalline  and  amorphous  silica.1  It  is  evident  from  these  observations 

1  Some  remarks  will  be  madt;  in  Chapter  XIV  ou  another  iise  of  the  word  chalcedony. 


342  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

that  crystalline  silica,  both  fibrous  and  granular,  forms  from  thermal  springs 
at  the  earth's  surface. 

cases. —  Besides  steam,  hydrogen  sulphide,  carbonic  anhydride,  and 
sulphurous  anhydride  escape  from  the  springs  and  fissures.  The  quanti- 
tative composition  of  the  gas  manifestly  varies  from  point  to  point,  and 
therefore  quantitative  analyses  were  not  made.  In  the  qualitative  analyses 
free  hydrogen  and  hydrocarbons  were  looked  for,  but  none  was  detected. 
Neither  were  oily  hydrocarbons  found  here  as  they  are  at  most  quicksilver 
deposits,  though  low  forms  of  vegetation  flourish  in  the  waters  of  the  hot 
springs  even  at  very  high  temperatures.  The  absence  of  hydrocarbons  from 
the  gases  and  deposits  is  a  very  important  fact.  The  sinter  rests  upon 
granite,  and  through  this  rock  the  springs  reach  the  surface.  If  the  hydro- 
gen sulphide  were  a  result  of  the  reduction  of  soluble  sulphates  by  organic 
matter,  hydrocarbons  would  almost  certainly  be  present,  as  was  pointed 
out  by  Bunsen  in  his  great  memoir  on  the  geysers  of  Iceland.  The  com- 
position of  these  gases,  therefore,  points  to  generation  from  inorganic 
material  at  the  seat  of  volcanic  activity  far  below  the  surface.  Whether, 
under  the  unknown  conditions  there  prevailing,  hydrogen  sulphide  can  be 
derived  from  sulphates  without  the  intervention  of  organic  matter  by  some 
reaction  not  yet  discovered,  or  whether  the  sulphur  comes  from  regions 
which  have  never  been  oxidized,  is  uncertain.  The  same  gases  are  percep- 
tible at  the  mine  as  at  the  more  active  springs  ;  it  is  possible,  however,  that 
a  portion  of  the  sulphurous  anhydride  at  the  mine  is  due  to  the  decomposi- 
tion of  hyposulphites. 

The  metalliferous  deposits — The  springs  now  flowing  emit  no  great  quantity 
of  water  and  many  of  the  vents  did  not  overflow  at  all  during  my  visit ; 
neither  does  the  water  seem  to  be  impelled  toward  the  surface  with  an}-  vio- 
lence and  in  most  cases  it  is  perfectly  clear.  The  mass  of  sinter  through 
which  the  water  attains  the  surface  is  also  many  yards  in  thickness.  The 
deposits  formed  in  the  vents,  particularly  when  they  are  narrow  cracks,  con- 
sequently consist  of  substances  which  have  been  held  in  solution  by  the 
waters  and  which  have  been  precipitated  by  cooling,  evaporation,  and,  to 
some  extent,  by  acidification  Large  quantities  of  these  deposits  were  col- 


ORES  AT  STEAMBOAT  SPRINGS.  343 

lected  at  different  points  and  were  analyzed  with  the  utmost  care.  In  the 
waters  themselves  one  could  expect  to  find  only  those  substances  which 
were  most  abundant  in  the  natural  precipitates,  because  they  represent  the 
concentration  of  much  larger  quantities  of  water  than  it  would  be  practicable 
to  evaporate  for  analysis.  The  spring  deposits  were  found  to  contain  the  fol- 
lowing metallic  substances  arranged  as  nearly  as  may  be  in  the  order  of  their 
quantity :  Sulphides  of  antimony  and  arsenic,  ferric  hydrate,  lead  sulphide, 
copper  sulphide,  mercuric  sulphide,  gold,  and  silver,  together  with  traces  of 
zinc,  manganese,  cobalt,  and  nickel.  In  the  spring  water  itself  only  antimony, 
arsenic,  and  traces  of  mercury  were  detected.  In  considering  the  analyses, 
it  must  be  remembered  that  the  greater  part  of  the  metallic  deposits  are  not 
at  the  vents  of  the  living  springs,  but  to  the  west  at  the  mine,  where  no 
springs  now  exist,  though  steam  and  solfataric  gases  in  small  quantities  still 
escape. 

Metalliferous  spring  deposits — Specimens  I  and  II  were  from  an  old  crevice  in 
the  plateau  of  sinter  near  the  railroad.  The  crevice  was  sealed  with  sinter 
and  the  ground  was  entirely  cold.  When  it  was  opened  no  water  was  found. 
The  deposit  was  r  true,  simple  fissure  vein  between  walls  composed  of  earlier 
sinters.  It  was  brick-red  in  color,  like  almost  all  of  the  metalliferous  de- 
posits of  the  plateau,  the  tint  being  due  to  red,  precipitated  sulphide  of 
antimony,  a  mineral  which  I  believe  has  received  no  name.1  The  color  of 
some  of  these  deposits  is  such  as  to  suggest  impure  cinnabar,  but  in  none 
of  those  near  the  railway  did  we  find  enough  mercuric  sulphide  to  account 
for  the  tint  Qualitative  analysis  showed  the  presence  of  mercury,  gold, 
silver,  copper,  lead,  arsenic,  antimony,  iron,  aluminium,  manganese,  zinc 
in  minute  quantity,  traces  of  cobalt  and  nickel,  lime,  magnesia,  lithium, 
sodium  and  potassium,  silica  and  sulphur.  A  minute  quantity  of  sulphates 
appeared  to  be  present.  Quantitative  separations  were  made  with  very 
large  samples.  The  object  was  to  obtain  weighable  amounts  of  the  metals, 
in  order  that  an  idea  might  be  obtained  of  their  relative  abundance.  The 
precise  estimation,  however,  has  only  a  general  value,  because  the  deposit 

1  Dr.  .1.  Sterry  Hunt  desiring  to  mention  this  mineral  in  bis  classification,  I  suggested  metaslibnite 
(Proc.  Am.  Philos.  Soc.,  vol.  25, 1888,  p.  l&J). 


344 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


is  manifestly  of  variable  composition, 
results: 


The  following  figures  give    the 


i. 

II. 

Weight  of  sample  

Crams. 
1  021  0000 

Qramt. 
3  403  0000 

Gold 

0  oOOft 

0  0034 

Silver    

0  0003 

0  001° 

0.0014 

0  0070 

0.  0899 

0  07°0 

Cuprio  sulphide  

0.0064 

0.  0424 

78  0308 

3.  5924 

Specimen  III  was  taken  from  a  crevice  at  some  points  of  which  hot 
water  and  gas  still  escape,  but  from  a  portion  of  the  fissure  no  longer 
active.  Qualitative  examination  showed  the  presence  of  mercury,  gold,  lead, 
copper,  antimony,  arsenic,  iron,  aluminium,  manganese,  traces  of  nickel, 
lime,  traces  of  strontium,  magnesium,  sodium,  potassium,  lithium,  caesium, 
rubidium,  free  silica,  and  free  sulphur.  The  bases  were  combined  as  sili- 
cates, carbonates,  sulphates,  sulphides,  chlorides,  borates,  and  phosphates,  the 
last  in  small  quantities.  The  color  of  the  material  showed  that  the  greater 
part  of  the  arsenic  and  antimony  was  in  the  form  of  sulphide.  Special 
determinations  of  the  mercury  were  made  with  portions  of  this  deposit 
After  drying  and  pulverizing,  the  carbonates  were  extracted  with  dilute 
chlorhydric  acid  and  the  heavy  metals  were  dissolved  in  aqua  regia  The 
precipitate  given  by  sulphureted  hydrogen  was  leached  with  cold,  yellow 
ammonium  sulphide  and  the  residual  sulphides  were  weighed.  A  portion 
of  this  residue,  heated  in  a  closed  tube  with  sodium  carbonate  and  pure 
iron  powder,  gave  a  sublimate  of  metallic  mercury.  This  sublimate  was 
tested  by  uniting  the  globules  to  larger  ones,  by  amalgamating  gold,  and 
by  conversion  into  mercuric  iodide  in  a  closed  tube.  From  another  por- 
tion mercurous  chloride  and  gold  were  precipitated  by  phosphorous  acid. 
The  gold  produced  the  characteristic  tint  and  a  button  of  metallic  gold  in 
a  pure  state  was  finally  extracted.  Another  portion  of  specimen  III,  ex- 
amined quantitatively,  gave  the  following  result: 

Grant  R. 
Weight  taken 2,  «!."i.  0000 

Mercuric  sulphide  found 0.0024 

Snl  jib  ides  of  arsenic  and  antimony 4.27-J~> 


OEES  AT  STEAMBOAT  SPRINGS.  345 

Another  sample  (IV)  from  the  same  crevices  which  contained  III,  but 
from  a  point  at  which  steam  and  sulphurated  hydrogen  bubbled  through 
the  hot  water,  showed  an  entirely  similar  composition;  it  contained  mercury, 
lead,  copper,  arsenic,  antimony,  iron,  aluminium,  calcium,  magnesium, 
sodium,  potassium  and  lithium,  free  silica,  and  free  sulphur.  The  bases 
were  combined  a>e  silicates,  sulphides,  sulphates,  carbonates,  chlorides, 
borates,  and  to  a  small  extent  as  phosphates. 

Specimen  V  was  from  one  of  the  springs  which  had  formed  a  basin, 
through  which  occasional  bubbles  rise  to  the  surface.  The  sediment  con- 
sisted of  layers  of  gray  and  yellow  material,  the  latter  being  tinted  by 
sulphide  of  arsenic.  It  contained  mercury  more  abundantly  than  those 
previously  mentioned,  and  also  lead,  copper,  arsenic,  antimony,  iron,  and 
aluminium,  a  trace  of  cobalt,  magnesium,  sodium,  potassium,  caesium,  lithi- 
um, free  silica,  and  sulphur.  The  bases  were  combined  as  silicates,  car- 
bonates, sulphides,  sulphates,  chlorides,  and  phosphates. 

At  one  point  on  the  plateau  a  mud  deposit  is  formed  by  deposition 
from  streams  issuing  from  two  of  the  more  active  springs.  Here  mica 
scales  exist,  showing  that  in  this  case  some  material  is  brought  up  in  sus- 
pension from  the  underlying  granite,  which  must  consequently  b'e  under- 
going decomposition ;  for  the  feeble  streams  of  water  which  rise  through 
it  are  certainly  incapable  of  wearing  granite  away  at  such  a  rate  that  the 
abraded  portions  would  be  visible  to  the  naked  eye.  This  mud  must  there- 
fore contain  products  of  decomposition  of  granite,  as  well  as  any  substances 
which  may  have  passed  through  the  granite  in  solution.  Qualitative 
analysis  showed  that  it  had  nearly  the  same  composition  as  the  other  de- 
posits. The  portion  soluble  in  acid  contained  mercury,  gold,  silver,  lead 
copper,  arsonic,  antimony,  much  iron,  aluminium,  a  trace  of  cobalt,  mag- 
nesium, calcium,  and  of  course  alkalis.  The  bases  were  combined  as 
silicates,  ca.i-bonat.es,  sulphides,  and  to  a  small  extent  as  phosphates. 

A  warm  spring,  which  is  known  as  the  Chicken  Soup  Spring,  issues  at 
the  base  of  the  plateau  close  to  the  railway,  the  water  of  which  is  drunk 
by  visitors  to  the  locality.  No  mercury  could  be  detected  in  the  sedi- 
ment; but  sulphides  of  arsenic  and  antimony  and  free  sulphur,  as  well  as 
low  vegetable  forms,  abound  in  it. 


346  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Free  sulphur  occurs  at  many  of  the  springs  and  also  at  tne  mine.  It 
is  of  course  produced  by  the  partial  oxidation  of  hydrogen  sulphides,  either 
by  atmospheric  air  or  by  sulphurous  anhydride.  The  quantity  is  nowhere 
large,  and  I  doubt  whether  more  than  a  pound  or  two  could  be  collected 
at  any  one  spot.  In  this  respect  there  is  a  great  difference  between  this 
locality  and  Sulphur  Bank,  where  a  great  quantity  of  sulphur  was  exploited. 
The  sulphur  is  found  chiefly  at  points  to  which  the  access  of  air  is  limited, 
as  should  be  the  case  according  to  the  thermochemical  relations  stated  on 
page  255. 

The  water. — The  water  analyzed  was  taken  from  a  spring  at  the  eastern 
edge  of  the  sinter  plateau,  which  had  formed  a  basin.  The  water  in  the 
basin  seemed  perfectly  limpid  and  the  overflow  was  gentle  and  nearly  con- 
stant. The  temperature  of  the  spring  was  found  to  vary  considerably,  the 
extreme  limits  noted  being  75°  and  84.5°  C.  In  order  that  the  water  might 
be  free  from  solid  impurities  it  was  siphoned  off  from  the  basin  into  a 
covered  funnel  and  was  filtered  directly  into  the  demijohns  used  to  trans- 
port it.  In  passing  through  the  siphon  the  water  was  inevitably  cooled, 
and  it  was  found  that  the  water  on  the  filter  paper  had  a  temperature  of 
from  30.5°  to  33°  C.  In  collecting1  the  water  in  this  manner  a  very  inter- 
esting fact  was  observed.  Near  the  lower  end  of  the  glass  siphon  a  red 
precipitate  formed.  Since  neither  air  nor  any  other  foreign  substance  had 
access  to  the  water  at  this  point,  the  precipitation  could  hardly  be  attributed 
to  any  other  cause  than  cooling.  The  precipitate  consisted  of  sulphides  of 
antimony  and  arsenic  and  silica,  the  last  being  deposited  chiefly  on  the 
upper  part  of  the  coated  portion  of  the  tube.  Here,  then,  ores  and  one  of 
the  most  important  of  gangue  minerals  were  deposited  in  an  opening  by 
natural  means,  and  I  had  the  pleasure  of  watching  the  actual  progress  of 
the  formation  of  an  ore  deposit.  On  the  filter  paper  also  a  similar  precipitate 
formed,  but  here  the  organic  matter  of  the  paper  and  atmospheric  influences 
were  at  work,  and  floating  dust  came  in  contact  with  the  fluid.  Even  the 
water  in  the  spring  basin  must  have  contained  organic  germs,  for  at  all  the 
springs,  so  soon  as  the  water  has  somewhat  cooled,  low  forms  of  vegetable 
life  flourish  and  form  red  and  green,  pulpy  sheets  of  slimy  matter.  The 
germs  of  these  organisms  are  no  doubt  abundant  in  the  atmosphere  and  fall 


WATER  OF  STEAMBOAT  SPRINGS.  347 

into  all  the  spring  basins.  On  the  inner  walls  of  the  siphon  tube  diatom- 
like  structures  were  visible  with  the  microscope.  The  cooling  of  the  water 
was  unquestionably. necessary  to  the  development  of  these  organisms,  and 
in  the  absence  of  air  it  seems  impossible  to  suppose  that  they  can  have 
grown  sufficiently  to  have  influenced  the  precipitation  of  the  sulphides. 

An  attempt  was  made  to  collect  a  considerable  quantity  of  precipitate 
by  simply  cooling  the  water  of  this  spring  as  described  above,  and  for  this 
purpose  a  number  of  long  siphons  were  set  in  operation.  But,  though  the 
precipitates  in  the  tubes  were  very  striking  in  appearance,  the  quantity  of 
precipitate  obtained  in  filtering  118  liters  was  only  about  nine  milligrams. 
It  was  almost  completely  soluble  in  yelloAV  ammonium  sulphide,  and,  to 
my  disappointment,  not  a  trace  of  mercury  could  be  detected.  Perhaps  this 
was  to  be  expected  in  view  of  the  proportion  which  cinnabar  bears  to  the 
sulphides  of  antimony  and  arsenic  in  the  other  deposits. 

The  following  results  were  obtained  from  analysis  of  the  water : 

Analysis  of  Steamboat  Springs  wahr. 

[Contents  of  10  liters  in  grams.l 

Silica,  SiOJ 3. 10G5 

Carbon  dioxide,  CO2 1.7759 

Boric  anhydride,  B2O3 2.1741 

Sulphuric  anhydride,  SO3 1.0339 

Hyposulphurous  anhydride,  S202 0.0307 

Sulphur  combined,  S  as  RHS 0.0327 

Hydrogen  sulphide,  H2S 0.0055 

Or  sulphur,  S 0.0052 

Chlorine,  Cl 9.5243 

Antiniouious  anhydride,  Sb2O3 0.0051 

Arsenious  anhydride,  As'O3 0. 0357 

Phosphoric  anhydride,  1MOB 0.  0063 

Mercuric  sulphide,  HgS Trace 

Alumina,  Al-O' 0.0025 

IVrvous  oxide,  FeO 0.0018 

Lime,  CaO 0.0958 

Magnesia,  MgO 0.0047 

Soda,  Na-0 9.1929 

Lithia,  LiJO.. 0.1541 

Potassa,  KZO 1.2460 

Caesium  and  rubidium  oxides,  Cs^O,  Rb2O Trace 

The  caesium  and  rubidium  in  this  analysis  were  detected  by  the  spec- 
troscope, but  the  quantity  present  was  too  small  for  determination.     The 


348  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

mercury  was  precipitated  by  phosphorous  acid  under  conditions  precluding 
the  precipitation  of  any  other  metal.  A  faint  cloudiness  indicated  its  pres- 
ence, but  no  weighable  quantity  came. down. 

The  basin  from  which  this  water  was  taken  was  small  and  contained 
perhaps  no  more  than  a  cubic  foot  of  water ;  but  the  overflow  was  also 
small,  and  a  part  of  the  water  in  it  must  have  been  exposed  to  the  air  at  a 
high  temperature  for  a  considerable  time.  Some  decomposition  was  there- 
fore to  be  expected.  If  solutions  of  alkaline  sulphides  be  allowed  to  oxi- 
dize, hyposulphites  are  well  known  to  form.  The  analysis  shows  hyposul- 
phurous  acid,  and  this,  I  think,  must  be  attributed  to  decomposition,  for 
its  formation  at  great  depths  appears  hard  to  explain,  nor  am  I  aware  that 
hyposulphites  have  ever  been  detected  under  conditions  which  suggest  their 
existence  in  nature  at  points  removed  from  oxidizing  influences  of  the  air. 
The  hyposulphurous  acid  is  undoubtedly  combined  with  sodium,  and  prob- 
ably represents  a  certain  amount  of  oxidized  sodium  sulphydrate.  The 
'decomposition  of  sodium  sulphydrate  is  well  known  to  be  attended  by  the 
formation  of  sodic  hydrate.  The  antimony  and  arsenic  were  certainly  in 
solution,  and  it  is  altogether  probable  that  they  were  originally  in  the  form 
of  sulpharsenides  and  sulphantimonides  of  sodium.  But  in  the  presence  of 
caustic  soda  these  sulphides  are  partially  decomposed  with  the  formation  of 
arsenites  and  antimonites-  The  sum  of  the  quantities  of  sulphur  found  in 
combination  with  metals  and  in  the  free  state  or  in  combination  with  hy- 
drogen is  just  sufficient  to  form  sulphantimonides  and  sulpliarsenide  of 
sodium,  and  the  presence  of  hydrogen  sulphide  is  explained  if  one  supposes 
the  sulphosalts  partially  decomposed,  as  suggested  above.  In  the  table 
given  below  I  have  supposed  the  arsenic  and  antimony  to  be  entirely  in  the 
condition  of  sulphosalts  and  that  the  hyposulphite  is  represented  by  sodium 
sulphydrate.  As  has  been  mentioned,  silica  is  precipitated  when  this  water 
is  cooled ;  but  when  the  fluid  reaches  the  surface  there  can  be  little  doubt 
that  it  all  exists  in  combination  with  the  alkalis  as  an  acid  silicate.  It 
is  not  improbable  that  this  compound  is  the  quadrisih'cate  of  sodium  It  is 
computed  as  such. 

Acid  sodium  carbonate  is  well  known  to  be  partially  decomposed  at 
high  temperatures,  and  it  is  therefore  by  no  means  unreasonable  to  suppose 


WATER  OF  STEAMBOAT  SPRINGS.  349 

that  a  part  of  the  sodium  salt  was  neutral.  This  supposition  also  accords 
with  that  made  with  reference  to  the  silica.  The  alumina  was  probably 
present  as  an  alkaline  aluminate,  but  the  quantity  found  was  so  small  that 
it  did  not  appear  worth  while  to  coinpute~1ts  hypothetical  compounds.  In 
Chapter  XV  it  will  be  shown  that  the  trace  of  mercury  in  this  water  is 
combined  as  a  double  sulphide  with  sodium,  which  is  of  the  form  HgS, 
^Xa2S.  The  value  of  n  in  this  case  is  probably  four.  No  comments  seem 
needful  on  the  state  of  combination  of  the  other  constituents  of  this  water. 
The  suppositions  made  lead  to  the  following  scheme  of  composition  as 
the  most  probable  prior  to  the  action  of  the  atmosphere  upon  the  fluid  : 

Probable  composition  of  the  water  prior  to  oxidation. 

Grams. 
Ferrous  cai-bonare,  FeCO3  ..................  ,  ................     0.0029 

Magnesium  carbonate,  MgCO3  ...............................  0.0099 

Calcic  carbonate,  CaCO3  ....................................  0.1577 

Calcic  phosphate,  Ca3P2O8  ..................................  0.0137 

Potassic  chloride,  KC'l  ......................................  1.9735 

Lithic  sulphate,  Li2SO4  .....................................  0.5650 

Sodic  chloride,  NaCl  ........................................  14.1475 

Sodic  sulphylrate,  NaHS  ...................................  0.0358 

Sodic  sulphate,  Na2SO<  .....................................  1.1147 

Sodic  bicarbonate,  NalICO3  .................................  2.9023 

Sodic  monocarbonate,  Na2CO3  ..............................  0.4314 

Sodic  biborate,  Na2B«OT  ....................................  3.1368 

Sodic  quadrisilicate,  NaaSW  ...............................  3.9090 

Sodic  sulphantimonide,  Na2SbS3  ............................  0.0100 

Sodic  sulpharsenide,  Na"AsS3  ................................  0.0866 

Alumina,  AW  ............................................  0.0025 

Sodium-mercury  sulphide,  HgS,  jiNa^S  ......................  Trace 


origin  of  the  water.  —  Old  residents  informed  me  that  the  quantity  of  water 
flowing  from  the  springs  varies  from  year  to  year,  being  greater  in  years  of 
heavy  rain-fall  than  in  dry  seasons  and  greater  in  spring  than  in  autumn. 
If  these  statements  be  accurate,  the  supply  must  come  from  the  surface 
and  no  very  long  time  can  intervene  between  precipitation  and  return  to 
the  surface.  It  is  natural  to  suppose  the  great  snowy  range  to  be  the  source 
of  supply.  The  fissures  underlying  the  range  may  afford  a  downward  pas- 
sage for  the  waters  to  the  heated  mass  from  which  the  basalt  came,  while 
the  fissures  associated  with  the  channel  through  which  the  basalt  was  ex- 


350  QUICKSILVER  DEPOSITS  OF  TIIE  PACIFIC  SLOPE. 

traded  furnish  a  shorter  road  back  to  the  surface.1  The  water  must  be  well 
filtered  ou  its  course,  since  there  is  no  evidence  that  organic  matter  is  car- 
ried to  the  source  of  heat. 

The  cinnabar  deposit. — The  quantity  of  mercuric  sulphide  in  the  deposits 
from  the  active  springs  is  very  minute,  and  there  is  in  this  district  nothing 
which  could  be  called  quicksilver  ore  in  a  commercial  sense,  excepting  near 
the  mine  workings  and  furnace  on  the  northern  central  portion  of  the  area 
mapped.  Cinnabar  is  deposited  in  considerable  abundance  only  in  the  de- 
composed granite,  though  a  few  paints  and  seams  have  penetrated  into  the 
basalt  at  the  southern  end  of  the  basin-like  depression.  By  no  means  all 
of  the  decomposed  granite,  however,  even  in  this  area,  shows  any  ore,  the 
cinnabar  occurring  only  as  impregnations  in  the  decomposed  area,  appar- 
ently along  the  courses  of  half-obliterated  fissures  in  the  soft  material. 
The  underground  workings  are  now  almost  wholly  inaccessible,  and  some 
prospecting  would  be  necessary  to  ascertain  anything  definite  with  regard 
to  the  amount  of  ore  available.  The  mode  of  occurrence  of  cinnabar  indi- 
cates that  the  deposition  did  not  proceed  pari  passu  with  the  decomposition 
of  the  granite,  but  followed  it.  Had  it  been  otherwise,  cinnabar  would  be 
found  generally  over  the  decomposed  area  and  the  impregnated  granite 
would  be  tolerably  firm,  instead  of  forming  a  gravel-like,  incoherent  mass. 
It  is  very  probable  that  at  depths  of  a  hundred  feet,  more  or  less,  the  char- 
acter of  the  deposit  would  be  found  to  differ  markedly  from  that  at  the  sur- 
face, for  the  phenomena  here,  as  at  Sulphur  Bank,  are  complicated  by  the 
action  of  sulphuric  acid  due  to  the  oxidation  of  sulphureted  hydrogen. 

Mctais  in  the  granite. — The  present  springs  are  certainly  decomposing  granite 
to  some  extent,  and  decomposition  of  this  rock  on  a  large  scale  has  occurred 
within  no  long  period.  It  seemed  probable  that  at  least  a  portion  of  the 
heavy  metals  found  in  the  deposits  were  derived  from  the  granite  and  pos- 
sible that  all  of  them  had  this  origin.  Rock  from  the  area  east  of  the  rail- 
road was  selected  because  it  was  fresh  and  well  removed  from  springs,  act- 
ive or  extinct.  Large  quantities  of  granite,  in  one  case  15.5  pounds,  were 
finely  pulverized  and  decomposed  either  by  aqua  regia,  which  does  not 

1  Compare  my  suggestion  as  to  tbe  source  of  the  water  entering  the  mines  on  the  Couistock  (Geol- 
ogy of  the  Comstock  Lode,  p.  243). 


METALS  IN  THE  GllANITE.  351 

decompose  the  mica,  or  by  hydrofluoric  and  sulphuric  acids.  Both  the 
resulting  solutions  were  examined  for  heavy  metals;  and  arsenic,  antimony, 
lead,  and  copper  were  found  in  those  prepared  by  each  of  the  above  meth- 
ods. but  neither  mercury  nor  gold  could  be  detected  in  either.  Experi- 
ments made  with  50  grams  of  hornblende  and  mica  separated  from  the  rock 
also  failed  to  detect  mercury  or  gold.  Lead  almost  if  not  quite  always 
contains  silver,  so  that  the  presence  of  lead  in  the  granite  points  to  the 
existence  of  silver  in  that  rock,  although  the  tests  available  were  not  suffi- 
ciently delicate  to  reveal  it.  Professor  Sandberger  has  actually  found  silver 
in  the  micas  of  German  granites,  as  well  as  arsenic,  lead,  copper,  and  other 
metals,  lie  has  also  detected  zinc  in  the  mica  of  gneiss.1  Silver  is  rarely 
if  ever  found  in  nature  unaccompanied  by  gold,  and  it  is  altogether  prob- 
able that  micas  in  which  Professor  Sandberger  found  silver  also  contained 
the  sister  metal.  According  to  Mr.  A.  Simundi  some  of  the  Idaho  granites, 
collected  at  long  distances  from  any  veins,  carry  determinate  quantities  of 
gold.- 

The  granite  of  Steamboat  Springs  exhibits  considerable  variations  in 
texture  and  mineral  composition,  as  do  most  other  granites.  This  and  other 
phenomena  indicate,  as  Scheerer  and  others  have  pointed  out,  that  granite 
has  never  been  thoroughly  fluid  and  is  not  uniform  in  composition.  It  is 
therefore  far  from  impossible  that  specimens  of  this  rock  from  other  points 
in  the  region  of  Steamboat  Springs  might  have  shown  gold,  silver,  and  zinc. 

Considering  that  the  granite  is  certainly  undergoing  decomposition  and 
partial  solution  by  action  of  the  springs  and  that  the  metals  most  abundant 
in  the  spring  deposits  are  also  found  in  the  granite,  it  seems  to  me  only 
reasonable  to  conclude  that  from  the  granite  the  springs  derive  the  arsenic, 
antimony,  lead,  and  copper  which  they  bring  to  the  surface.  The  other 
metals  are  found  in  the  deposits  in  far  smaller  quantities  than  those  just 
enumerated.  Though  not  detected  in  the  granite  here,  all  of  them  except- 
ing quicksilver  are  known  to  occur  elsewhere  in  granite  or  gneiss.  It  is 
also  worth  noting  that  silver,  gold,  and  zinc,  are  very  frequently  associated 
in  nature  with  arsenic,  antimony,  lead,  and  copper.  The  prevalence  of  this 


iilicr  Ki/^iiuge,  p.  25. 
Euimons  and  Becker,  Statistics  and  Technology  of  the  Precious  Metals,  p.  54. 


352  (JUICKS1LVEU  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

association  seems  to  point  to  the  supposition  that  these  metals  are  often 
derived  from  the  same  source.  It  is  therefore  much  more  probable  that  the 
silver,  gold,  and  zinc  also  were  derived  from  the  granite  at  Steamboat  than 
that  they  came  from  the  unknown  regions  beneath  it  or  from  some  mass  of 
lava  crossing  it.  As  for  the  quicksilver,  I  am  not  a.  ware  that  it  has  ever 
been  detected  as  a  constituent  of  a  massive  rock  ;  but  it  is  found  at  very 
many  points  the  world  over  in  association  with  gold,  copper,  arsenic,  and 
antimony,  or  some  of  them.  All  the  circumstances  at  Steamboat  seem  to 
point  to  the  granite  as  its  probable  source,  and,  so  far  as  I  know,  nothing 
suggests  a  different  origin. 

conclusions  —  As  Messrs.  J.  A.  Phillips1  and  Laur2  have  pointed  out,  Steam- 
boat affords  instances  of  the  formation  of  true  fissure  veins  by  hot  springs 
at  the  present  da}'.  While  it  is  quite  probable  that  some  veins  are  formed 
in  a  different  manner,  it  is  substantially  certain  that  many  deposits  have 
been  generated  in  this  way.  The  composition  of  the  waters,  with  special 
experiments  devised  for  the  purpose,  also  leads  to  definite  conclusions  con- 
cerning the  soluble  compounds  of  the  metals  contained  in  the  waters,  as  will 
be  shown  in  Chapter  XV.  Steamboat  Springs,  too,  affords  a  striking  illus- 
tration of  lateral  secretion.  This  term  is  sometimes  limited  to  segregations 
affected  by  cold  solutions,  but  quite  improperly,  for  the  extraction  and  dep- 
osition of  ore  from  the  rocks  adjoining  fissures  by  hot  solutions  are  just  as 
much  lateral  secretion  as  if  the  prevailing  temperature  were  low.  The  term 
is  used  by  von  Cotta  without  any  limitation  as  to  temperature.  As  it  has 
been  employed  by  Mr.  S.  F.  Emmons  and  myself  also,  a  limitation  as  to 
temperature  has  never  been  implied. 

comparison  with  the  comstock.  —  There  are  noteworthy  similarities  and  differ- 
ences between  the  deposits  of  Steamboat  and  of  the  Comstock  lode.  At 
Steamboat  gold  is  present  in  much  larger  quantities  than  silver,  as  it  is  in 
all  the  deposits  of  the  gold  belt  of  California.  At  the  Comstock  the  pro- 
portion of  gold  to  silver  by  weight  is  only  about  1  to  20.  At  Steamboat 
arsenic  and  antimony,  lead,  copper,  and  mercury  are  the  most  abundant 
metals,  while  on  the  Comstock  mercury  is  not  found  at  all  and  the  prevail- 
ing ore  is  auriferous  argentite.  As  I  showed  in  my  memoir  on  the  Com- 


1  Ore  Deposits,  1884.  "  Annalcs  drs  mines,  vol.  ;!,  W>:'>,  p.  •!•.':;. 


STEAMBOAT  SPKINGS  AND  THE  COMSTOOK.  353 

stock,  it  is  probable  that  the  ore  was  there  leached  from  the  diabase  hanging 
wall  by  the  action  of  ascending  waters  of  very  high  temperatures,  charged 
with  alkaline  solvents,  and  was  not  deposited  by  sublimation  or  distillation, 
as  Baron  von  Richthofen  surmised.  THe  difference  in  origin  of  the  two  ore 
deposits  sufficiently  explains  their  difference  in  character.  It  is  of  course 
possible  that  a  part  of  the  ore  of  the  Comstock  may  have  been  derived  from 
granite,  and  it  is  noteworthy  that  the  ore  of  the  Justice  mine,  which  is  near 
the  granite  area,  was  much  baser  than  and  quite  different  from  that  of  the 
mines  of  Gold  Hill  and  Virginia.  I  shall  be  obliged  to  return  to  this  sub- 
ject in  Chapter  XVI. 

MON  XIII 23 


CHAPTER  XII. 

DESCRIPTIVE  GEOLOGY  OF  THE  OATHILL,  GREAT 
WESTERN,  AND  GREAT  EASTERN  DISTRICTS. 

In  addition  to  the  five  districts  described  in  the  previous  chapters, 
small  areas  surrounding  the  Napa  Consolidated,  Great  Western,  and  Great 
Eastern  mines  were  mapped.  The  topography  of  these  maps  was  executed 
rapidly  and  without  any  effort  to  attain  the  degree  of  accuracy  demanded 
in  the  larger  maps.  It  is  nevertheless  very  fairly  done,  and,  excepting  in 
some  minute  details,  the  localities  are  excellently  represented.  I  intrusted 
the  study  of  the  geology  of  these  districts  to  Mr.  Turner.  On  going  over 
the  surface  area  and  the  mines  with  him,  at  the  completion  of  his  examina- 
tions, I  could  not  see  that  anything  had  been  omitted  or  misrepresented. 
This  chapter  is  mainly  prepared  from  his  reports. 

OATHILL. 

The  neighborhood  of  oathiii. —  The  region  including  Oathill,  the  .<Etna  mines, 
and  the  hot  springs  of  Lidell,  an  area  of,  say,  four  miles  by  three,  is  one  of 
the  most  interesting  in  the  entire  quicksilver  belt,  and,  had  its  character 
been  sufficiently  understood  at  an  earlier  period,  an  atlas  sheet  would  have 
been  devoted  to  it.  The  deposits  are  numerous  and  differ  very  greatly 
from  one  another  in  external  form  and  in  the  character  of  the  inclosing 
rocks;  some  of  them  are  also  manifestly  connected  in  the  closest  manner 
with  volcanic  phenomena.  These  circumstances  lend  the  deposits  special 
significance.  The  JEtna  mines  will  be  described  in  the  next  chapter,  where 
also  a  sketch  map  showing  the  relative  positions  of  the  deposits  will  be 
found;  but  a  few  notes  on  these  occurrences  are  needful  to  a  proper  appre- 

354 


1 


a 


1  ^ 
2 

X 

a 

o 


f»y 


OATHILL  DISTRICT.  355 

ciation  of  the  Oathill  mines.  Hot  sulphur  springs  issue  from  an  opening 
of  the  abandoned  Valley  mine  at  Lidell.  The  rock  is  highly  metamorphie 
and  shows  small  •quantities  of  cinnabar  associated  with  black  opal.  The 
yEtna  Company's  deposits  are  in  part  in  metamorphie  rocks,  showing  at 
present  no  evidence  of  volcanic  action,  unless  the  evolution  of  large  quan- 
tities of  inflammable  gas  is  to  be  regarded  as  due  to  causes  coming  under 
this  category.  These  metamorphie  rocks,  as  well  as  the  strata  at  Oathill, 
are  members  of  the  Knoxville  series.  Two  of  the  ore  deposits  are  in  part 
impregnations  and  in  part  of  the  irregular,  reticulated  type.  In  two  of  the 
mines  of  the  ^Etna  Company  the  deposits  form  veins  or  vein-like  impreg- 
nations at  the  contact  between  the  basalt  dikes  and  sandstone,  the  ore 
occurring  both  in  the  decomposed  basalt  and  in  the  adjacent  sedimentary 
material.  No  hot  water  or  gas  now  reaches  these  veins,  though  they  must 
be  of  very  recent  origin.  There  is  no  reason  whatever  to  suppose  that  the 
various  deposits  of  this  small  district  are  due  to  essentially  different  causes, 
and  the  common  cause  seems  beyond  question  the  action  of  thermal 
springs 

strata  of  oathiii. — The  deposits  of  Oathill  are  inclosed  in  a  gray,  rather 
friable  sandstone,  which  is  comparatively  little  altered  or  disturbed  in  the 
neighborhood  of  the  mines,  but  passes  over  into  intensely  metamorphosed 
rocks  in  all  directions.  Veinlets  of  quartz,  however,  intersect  the  sandstone 
in  some  places,  indicating  that  the  general  metamorphism  of  the  country 
was  feebly  felt  even  here.  The  sandstones  are  not  fossiliferous,  though 
Atorlla  roittnitrifu  occurs  at  no  great  distance  and  evidently  in  the  same 
series  of  strata.  A  small  amount  of  shale  accompanies  the  sandstone.  The 
area  of  unaltered  rock  is  small,  the  ridge  at  the  north  end  of  the  map  (Plate 
V)  being  highly  silicified,  while  the  southern  border  is  in  serpentine,  which 
forms  a  part  of  the  belt  of  this  rock,  extending  from  the  .^Etna  mine  north- 
westerly to  St.  Helena  Creek. 

Lavas. — The  hill  in  which  the  deposits  occur  is  covered  over  with  a  thin 
layer  of  basalt.  This  sheet  is  cracked  up  into  large  bowlders,  many  of  them 
weighing  many  tons  each,  and  the  underlying  sandstone  is  exposed  at  a  num- 
ber of  points.  The  basalt  is  for  the  most  part  gray  and  vesicular,  but  is  found 
in  the  more  usual  dark,  compact  form  at  a  few  points.  At  the  northwest  cor- 


356  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

ner  of  the  map  this  thin  sheet  is  in  contact  with  a  plateau  of  basalt,  in  which 
the  rock  is  of  much  greater  thickness.  This  mesa  is  about  a  mile  square 
and  is  bounded  on  all  sides  by  precipitous  walls.  To  the  north  of  the  mines 
is  a  larger  area  of  pyroxene-andesite,  a  tongue  of  which  enters  the  region 
mapped. 

Deposits  of  the  Napa  Consolidated. Tll6  deposits  of  Oatllill  ai'G  tll.6  Md'CUry  Vein, 

the  Manzanita  vein,  and  the  Accidental  vein,  which  are  the  property  of  the 
Napa  Consolidated  Mining  Company,  and  the  Eureka  claim,  which  contains 
a  deposit  similar  to  those  of  the  Napa.  The  principal  mine  is  upon  the  two 
veins  first  mentioned. 

The  Mercury  and  Manzanita  deposits  are  on  t\vo  nearly  parallel  fissures 
in  the  unaltered  sandstones  of  Oathill.  They  strike  north  west-southeast 
magnetic  and  dip  at  a  high  angle,  usually  more  than  45°.  The  strata,  both 
in  the  mine  and  outside  of  it,  are  nearly  horizontal,  excepting  close  to  the 
fissures.  Here  the  faulting  which  has  taken  place  between  the  walls  of  the 
fissures  has  flexed  the  strata.  Those  of  the  hanging  wall  are  bent  upward 
toward  the  fissure  and  those  on  the  foot-wall  are  flexed  downward,  thus 
indicating  the  direction  of  the  movement.  The  walls  of  the  fissures  are 
almost  everywhere  well  marked  by  slickensides  and  the  interval  between 
them  is  chiefly  filled  with  products  of  their  attrition,  sometimes  in  the  form 
of  clay.1  Often  also  fragments  of  sandstone  and  shale,  showing  the  original 
stratification,  are  found  betv/een  the  walls.  The  attrition  mixture  is  im- 
pregnated with  silica,  calcite,  pyrite,  and  cinnabar.  The  silica  is  found 
mainly  in  stringers,  which  intersect  the  vein  matter  in  surfaces  parallel  to 
the  walls  and  sometimes  give  a  cross-section  of  the  vein  a  stratified  appear- 
ance. A  portion  of  the  pyrite  is  oxidized,  and  iron  oxide,  ferrous  sulphate, 
and  magnesium  sulphate  have  resulted  from  this  process.  The  seams  car- 
rying most  ore  are  often  marked  by  iron  stains. 

At  a  number  of  points  the  cinnabar  has  followed  the  stratification  of 
the  inclosing  sandstone  away  from  the  veins,  forming  horizontal  chambers, 
which  are  sometimes  100  feet  in  length  and  50  in  height.  In  the  Mercury 
several  such  chambers  occur  in  the  foot-wall.  The  only  one  accessible  in 

1  It  may  be  well  to  call  attention  to  the  fact  that  the  clay  of  mines  very  frequently  contains  little 
or  no  kaolin.  Any  soft,  tough  mass  is  called  clay  by  miners  (see  Geology  of  the  Comstock  Lode, 
p.  217). 


NAP  A  CONSOLIDATED  MINE. 


357 


the  Manzanita  was  in  the  hanging  wall.  These  chambers  are  true  impregna 
tions  in  the  soft  sandstone.  When  the  tenor  of  the  rock  is  only  1  or  2  per 
cent,  of  quicksilver,  the  cinnabar  is  hardly  visible  on  a  fractured  surface,  but 
when  such  rock  is  bruised  a  red  stain  appears.  The  color  in  the  pick-marks 
in  such  cases  is  regarded  as  a  trustworthy  guide  to  the  value  of  the  ore. 


Fie.  II    niK-;r:iininatir  cross -section  on  magnetic  northeast  and  southwest  line  through  the  main  workings  of  the  N:ipa 

Consolidated  mine.    Scale  100  feet  to  1  inch. 

The  two  veins  of  this  mine  answer  to  "  rake  veins,"  while  the  adjacent 
chambers  correspond  to  "  pipe  veins,"  at  least  as  these  terms  are  defined 
by  von  Cotta.  Pyrite  as  well  as  cinnabar  impregnates  the  walls  to  some 
extent,  No  hot  water  or  sulphur  gases  enter  this  mine. 

cross-section. — The  accompanying  diagram  (Fig.  14)  illustrates  the  charac- 
ter of  these  veins,  but  portions  of  the  ground  were  inaccessible,  and  it  does 


358  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

not  profess  to  be  perfectly  accurate.  The  Mercury  vein  was  barren  below 
the  400-foot  level  and  has  not  been  tra'ced  below  the  500.  The  Manzanita 
was  followed  to  the  875-foot  level,  the  deepest  in  the  mine.  This  vein  was 
richest  between  the  400  and  500  levels  and  was  barren  below  the  750. 

It  is  evident  that  the  ore  in  this  mine  reached  its  present  position  along 
the  fissures  from  below.  There  is  no  reason  to  suppose  that  the  ore  was 
deposited  only  near  the  surface,  and  vigorous  prospecting  on  the  well 
defined  fissures  will  most  likely  disclose  other  ore  chambers  adjacent  to  the 
veins,  unless  the  sandstone  should  become  so  dense  as  to  preclude  impreg- 
nations. Had  the  strata  been  nearly  vertical,  instead  of  almost  horizontal, 
at  this  locality,  it  is  evident  that  the  fissures  would  have  more  or  less  nearly 
coincided  with  the  planes  of  stratification  and  that,  instead  of  a  well  marked 
vein,  impregnated  strata  would  have  resulted,  though  everything  except  the 
dip  of  the  beds  had  remained  the  same.  The  relation  between  those  two 
forms,  of  deposit  is  thus  of  the  closest  description. 

Minor  deposits. — The  Accidental  is  a  vein  lying  to  the  south  of  the  Mer- 
cury, and  its  projection  would  intersect  the  latter  at  a  considerable  angle. 
Cinnabar  has  been  found  in  it  and  it  is  regarded  as  a  hopeful  prospect. 
Other  faults  have  been  found  containing  cinnabar,  some  of  which  are  par- 
allel to  the  Mercury  and  the  Manzanita. 

The  Eureka  claim  is  on  the  same  hill  as  the  Napa  and  in  rock  of  the 
same  kind.  The  deposit  is  on  an  irregular,  though  well  defined  fault  nearly 
at  right  angles  to  the  Napa  veins.  A  part  of  the  ore  from  this  mine  is  in  a 
sandstone  breccia,  but  it  is  generally  quite  the  same  as  that  from  the  Napa. 

The  Ivanhoe  is  on  the  south  side  of  James  Creek,  also  in  unaltered 
sandstone.  It  has  produced  only  a  small  quantity  of  ore. 

GREAT    WESTERN. 

Geological  position. — The  Great  Western  has  been  the  largest  producer  among 
the  mines  of  the  Mayacmas  belt.  It  has  yielded  over  fifty  thousand  flasks 
of  quicksilver  and  is  by  no  means  exhausted.  The  underlying  sedimentary 
rocks  of  the  district  are  for  the. most  part  highly  metamorphosed.  A  little 
unaltered  rock  exists,  but  no  fossils  were  found  in  it.  The  lithological  and 
physical  character  of  the  beds  so  strongly  resembles  that  of  areas,  not  far 


0 

- 

- 


I  r  I 


• 


m 


i    ?      R 


I 


GREAT  WESTERN  DISTRICT.  359 

distant,  which  are  known  to  belong  to  the  Knoxville  series  (Neocomian), 
that  they  may  fairly  be  ascribed  to  that  series,  especially  as  there  is  noth- 
ing' to  indicate  the  presence  of  any  earlier  rocks  in  this  part  of  the  country. 

The  metamorphic  rocks  include  granular,  phthanitic,  and  serpentinoid 
varieties.  As  is  usual  in  the  Coast  Ranges,  no  definite  lines  can  be  drawn 
between  these  varieties ;  nevertheless  serpentine  prevails  so  greatly  in  one 
portion  of  the  district  that  it  seemed  to  me  expedient  to  delineate  it  upon 
the  map  (Plate  VI).  The  outline  of  the  serpentinized  area,  however,  here, 
as  in  the  districts  described  in  former  chapters,  is  not  to  be  regarded 
as  representing  a  sharp  and  complete  division,  but  only  as  indicating  the 
prevalence  of  one  phase  of  metamorphism  in  a  part  of  the  district.  The 
unserpentinized  area  is  chiefly  occupied  by  silicified  rocks.  The  dip  of  the 
strata  is,  as  usual  in  such  areas,  very  irregular,  but  the  prevailing  inclina- 
tion is  to  the  south,  or  toward  Mt.  St.  Helena,  at  an  angle  approaching  45°. 

Lavas. —  Upon  the  sedimentary  rocks  lie  lavas.  The  andesite  seems  to 
have  once  covered  a  larger  area  than  it  now  does  and  to  have  been  par- 
tially removed  by  erosion,  leaving  many  patches  of  extremely  small  size. 
The  andesite  is  pyroxenic,  and  the  greater  part  of  it  is  glassy,  though 
asperitic  modifications  and  tufa  also  occur,  A  portion  of  the  asperite  is 
Luninated,  as  is  so  common  near  Clear  Lake  and  at  Steamboat  Springs. 
More  unusual  is  the  occurrence  of  contorted  beds  in  this  asperite,  as  if  plas- 
ticity had  been  retained  after  the  structure  was  established.  It  is  possible, 
however,  that  the  original  form  of  the  lamina;  was  an  undulating  one.  A 
portion  of  the  andesite  forms  fine  columns,  which  is  somewhat  unusual  on 
the  Coast  Ranges,  though  common  enough  along  the  Sierra. 

Basalt  is  also  represented  in  this  district.  It  crowns  the  highest  eleva- 
tion on  the  map,  a  hill  composed  of  andesite,  thus  giving  clear  proof  of  the 
order  of  succession  of  the  lavas,  which  indeed  would  not  be  questionable 
even  in  the  absence  of  cases  of  direct  superposition.  A  portion  of  the 
basalt  is  vesicular,  and  secondary  crystals  are  sometimes  found  in  the 
cavities. 

ore  deposits. — The  ore  deposit  of  the  Great  Western  consists  of  tabular 
masses  of  ore,  situated  at  the  contact  between  very  slightly  altered  sand- 
stone and  a  heavy  body  of  serpentine.  The  serpentine  is  accompanied  by 


360 


QtriCKSILVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


a  belt  of  black  opaline  material  frequently  known  to  the  miners  of  northern 
California  as  quicksilver  rock.  This  opaline  layer,  being  firmer  and  less 
easily  decomposed  than  the  surrounding  masses,  projects  from  the  adjoining 
rocks  as  a  cropping.  The  ore  bodies  are  in  direct  contact  with  the  sand- 
stone, but  are  for  the  most  part  inclosed  on  three  sides  by  serpentine.  In 
a  few  cases  small  bodies  of  the  ore  extend  into  the  opaline  zone,  which  is, 

as  a  rule,  separated  from  the  ore  by  a  few  feet 
of  unaltered  serpentine.  These  relations  are  best 
shown  by  the  accompanying  cross-section  (Fig.  15). 
The  distribution  of  ore  in  the  direction  of  the 
strike  is  irregular,  the  ore  bodies  being  divided 
from  one  another  by  barren  ground,  and,  as  has 
been  the  case  in  so  many  mines,  they  were  richest 
near  the  surface.  The  following  longitudinal  sec- 
tion of  the  deposit  shows  the  distribution  of  the 
chimneys  of  ore  so  far  as  they  have  been  traced 
Fig.  16). 

The  ore  has  been  for  the  most  part  cinnabar, 
but  at  one  point  a  body  of  rock  strongly  impreg- 
nated with  native  quicksilver  was  found.  Pyrite 
is  abundant.  Some  of  the  cinnabar  is  so  embedded 
in  quartz  as  to  show  that  the  deposition  of  the  two 
minerals  was  simultaneous.  Bitumen  occurs,  particularly  in  cavities  in  the 
opaline  belt.  The  new,  seemingly  very  ill  defined  species  of  bitumen, 
posepnyte,  was  described  from  this  mine  by  Schrockinger.  This  bitumen 
is  said  to  consist  of  a  mixture  of  ozocerite  and  a  substance  soluble  in 
ether  which  has  the  formula  C22H3C04. 

Specimens  collected  at  the  Great  Western  were  examined  by  Dr.  Mel- 
ville with  the  following  results  : 

The  substance  is  reddish  brown,  resinous,  soft,  elastic,  has  a  specific 
gravity  of  0.985,  and  is  highly  electrified  by  friction  in  an  agate  mortar. 
On  platinum  foil  it  volatilizes  partially  at  low  temperatures  with  a  rather 
suffocating,  aromatic  odor ;  at  a  higher  temperature  it  becomes  black  and 
fuses  and  boils  like  rubber;  at  a  dull-red  heat  an  incombustible,  light-brown 


FIG.  J5.  Vertical  cross  -  section 
through  shaft  No.  3,  Great  Western 
mine.  Scale,  200  feet  to  1  inch. 


GREAT  WESTERN  MINE. 


361 


ash  remains.  In  a  closed  tube  a  yellow-brown  oil  distills  off  with  an  odor 
somewhat  like  burnt  rubber,  leaving  a  black,  carbonaceous  residue.  Noth- 
ing volatilizes  at  190°  C.,  so  far  as  could  be  determined.  In  the  retort  a 
light-colored,  brownish-yellow  liquid  distills  over  considerably  below  red 
heat;  at  about  low  red  heat  a  dark-brown  liquid  conies  over  and  a  black 
residue  remains.  Both  liquids  are  heavy  and  viscous.  The  lighter-colored 


\  ORE     BOO 


Fin.  10.  Vertical  longitudinal  section  of  the  Great  Western  quicksilver  mine,  N.  65°  W.     Scale,  200  feet  to  1  inch. 

liquid  yields  vapor  at  140°  C.,  rapidly  at  190°  C.,  the  product  smelling  like 
coal-tar  oils,  while  carbonaceous  matter  remains  after  complete  distillation 
at  temperatures  gradually  rising  above  190°  C.  All  these  facts  indicate 
decomposition  by  heat.  Alcohol  dissolves  the  substance  partially.  The 
alcoholic  extract  when  evaporated  yields  an  oil.  Ether  removes  an  olive- 
colored  oil,  the  substance  not  wholly  dissolving. 

Xo  nitrogen  or  sulphur  was  detected.     Carbon,  hydrogen,  oxygen  (by 
difference),  and  ash  (silica  and  ferric  oxide)  were  determined  with  the  fol- 


lowing result : 


Per  cent. 

Carbon 85.60 

Hyilnigon 10.71 

Oxygen 3.S2 

Ash 47 

100. 00 


362  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

This  mineral  is  doubtless  posepnyte,  although  many  of  its  physical 
characteristics  are  not  altogether  like  those  ascribed  to  that  mineral. 

The  deposit  of  the  Great  Western  appeared  to  be  a  tabular,  reticulated 
mass,  connected  with  a  fissure  system.  It  was  certainly  precipitated  from 
solutions,  and  these  were  probably  dependent  upon  volcanic  action  which 
attended  the  eruption  of  the  adjacent  lavas.  No  hot  waters  or  gases,  how- 
ever, now  enter  the  mine. 

THE    GREAT   EASTERN. 

importance  and  position — This  mine  is  in  Sonoma  County,  about  three  miles 
north  of  Guerneville.  There  is  another  mine  of  the  same  name  in  Lake 
County,  near  the  Great  Western,  which  will  be  referred  to  in  the  next 
chapter.  The  Great  Eastern  of  Sonoma  County  has  a  considerable  eco- 
nomic importance,  having  yielded  over  eleven  thousand  flasks  of  metal  and 
having  been  able  to  continue  production  in  spite  of  the  great  depression  in 
the  price  of  quicksilver  during  the  past  few  years.  The  Mt.  Jackson  mine, 
which  is  on  the  same  ledge  as  the  Great  Eastern,  has  also  produced  f>97 
flasks,  but  has  not  been  worked  of  late  years.  The  deposit  upon  which 
these  two  mines  are  situated  is  somewhat  remarkable  for  its  isolation. 
Not  only  is  it  above  twenty  miles  from  the  nearest  quicksilver  mine,  but 
it  lies  away  from  the  cou-rse  of  any  line  of  deposits.  It  is  also  somewhat 
distant  from  manifestations  of  volcanic  activity,  the  nearest  known  lavas 
being  about  six  miles  east  of  the  Great  Eastern. 

Gen«ai  geology — The  district  surveyed  presents  little  interest  from  the 
point  of  view  of  general  geology.  The  surface  is  exclusively  occupied  by 
the  series  of  irregularly  metamorphosed  rocks  so  prevalent  in  the  Coast 
Ranges.  Slightly  altered  sandstones  and  shales,  impure  limestones,  gran- 
ular metamorphics,  schists  carrying  glaucophane  and  garnet,  phthanites, 
and  serpentine  are  all  represented.  So  thoroughly  mingled  are  these  vari- 
ous substances,  however,  and  so  numerous  are  the  transitions  that  it  would 
be  entirely  impracticable  to  represent  the  varieties  by  colors  on  the  map 
(Plate  VII). 

Although  a  portion  of  the  beds  are  so  little  altered  that  fossils  might  have 
been  tolerably  preserved  in  them,  no  organic  remains  could  be  detected. 


8 
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UII7BR3ITY 


GREAT  EASTERN  DISTRICT.  363 

Consequently  their  age  is  a  matter  of  inference.  The  fac.ts  bearing  on  this 
question  are  as  follows:  Along  the  coast  of  Sonoma  County,  to  the  south 
of  Ft.  Ross  and  a  little  more  than  six  miles  from  the  Great  Eastern,  I  found 
a  series  of  unaltered  sandstone  beds  lying  -»nconforma,bly  upon  the  meta- 
morphic  series.  The  overlying  strata  are  fossilifereus  at  some  points  and 
have  been  named  the  Wallala  beds.  Dr.  White  has  determined  the  fossils 
which  they  contain  as  Middle  Cretaceous.  The  underlying  metamorphic 
series  is  older,  arid  there  can  be  little  doubt  that  it  is  at  least  as  old  as  the 
Knoxville  series.  It  may  possibly  be  older,  but  all  the  characteristics  of 
the  rock  are  absolutely  identical  with  those  of  the  material  at  numerous 
points  from  Colusa  County  to  San  Luis  Obispo,  in  which  Amelia  has  been 
found.  There  is,  furthermore,  nothing  in  this  part  of  the  country  suggest- 
ing the  presence  of  strata  earlier  than  the  Knoxville  series.  So  far  as  there 
is  any  evidence  as  to  the  age  of  the  rocks  at  the  Great  Eastern,  therefore, 
they  are  to  be  regarded  as  Neocomian. 

Quicksilver  r0ck. —  In  this  district  there  are  numerous  occurrences  of  opal- 
ized  rocks.  Of  these  many  are  small,  seemingly  isolated  patches.  In  two 
cases  this  material  forms  defined  ledges,  standing  up  from  the  surface  on 
account  of  the  resistance  which  it  offers  to  decomposition  and  erosion. 
These  ledges  strike  nearly  east  and  west  magnetic,  which  seems  to  be  the 
prevalent  strike  of  the  strata  also.  In  one  of  these  are  the  deposits  of  the 
two  mines.  At  the  surface  the  metalliferous  ledge  is  nearly  vertical,  but 
at  lower  levels  it  dips  to  the  north.  It  lies  between  a  hanging  wall  of  sand- 
stone and  a  foot-wall  of  serpentine. 

ore  deposits. —  It  will  be  remembered  that  at  the  Great  Western  also  a 
layer  of  opalized  rock  lies  between  serpentine  and  sandstone.  At  the  Great 
Eastern,  however,  the  ore  is  inclosed  in  the  dark,  opaline  mass,  instead  of 
being  adjacent  to  it.  The  ore  body  was  continuous  from  the  surface  to  the 
lowest  workings,  a  vertical  distance  of  450  feet.  The  ore  does  not  form  a 
nearly  vein-like  sheet  in  the  ledge,  but  an  irregular  pipe,  the  axis  of  which 
is  inclined  to  the  horizon  at  an  angle  of  about  50°.  So  far  as  it  has  been 
developed  it  is  entirely  embedded  in  the  opalized  rocks  and  does  not  touch 
either  the  sandstone  or  serpentine.  The  ore  does  not  appear  to  have  been 
deposited  simultaneously  with  the  amorphous  silica,  but  in  openings  in  the 


364 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


material.  It  is  accompanied  by  pyrite  and  quartz.  Bitumen  is  also  found, 
especially  in  covities  in  the  opaline  mass. 

The  deposit  of  the  Mt.  Jackson  seems  to  have  been  similar  to  that  of 
the  Great  Eastern,  but  of  smaller  extent.  The  explorations  do  not  appear 
to  have  been  sufficient  to  decide  whether  there  are  or  are  not  other  similar 
pipes  of  ore  in  this  layer  of  rock. 

The  following-  cut  (Fig.  17)  represents  a  vertical  cross-section  of  the 
ledge  upon  which  the  ore  pipe  is  projected : 


Flo.  17.  Vertical  cross-section  of  the  Great  Eastern  mine.     Scale,  150  feet  to  1  inch. 

Probable  history. — The  dark,  opaline  or  chalcedonic  "  quicksilver  rock"  of 
this  locality  seems  to  have  resulted  from  a  silicification  of  several  rocks, 
chiefly  perhaps  of  serpentine.  Both  here  and  at  the  Great  Western  this 
silicification  seems  to  have  preceded  the  deposition  of  ore,  though  somewhat 
closely  connected  with  it.  The  deposition  of  silica,  in  part  amorphous, 
probably  succeeded  a  movement  attended  by  the  development  of  hot 
springs.  Renewed  movements  followed,  dislocation  taking  place  in  tho 
opalized  beds  at  the  Great  Eastern,  close  to  those  at  the  Great  Western, 
and  these  later  movements  were  succeeded  by  the  deposition  of  ore.  This 
interpretation  of  the  structure  is  supported  by  the  existence  of  other  ledges 
of  the  opalized  material  in  which  no  cinnabar  seems  to  occur. 


CHAFFER  XIII. 

OTHER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Besides  the  eight  districts  described  in  the  foregoing  chapter,  there  are 
many  less  important  localities  in  which  cinnabar  has  been  found  and  from 
which  more  or  less  metal  has  been  extracted.  A  considerable  number  of 
these  have  been  visited  by  myself  or  by  members  of  my  party  and  others 
have  been  described  by  previous  observers.  Such  notes  on  these  occur- 
rences as  are  available  w\\\  be  presented  in  this  chapter.  Many  facts  con- 
nected with  these  deposits  are  of  great  geological  interest,  but,  on  the  other 
hand,  a  large  number  of  the  deposits  are  so  similar  that  it  is  impossible  to 
avoid  monotony  in  their  description. 

The  quicksilver  belt. — The  quicksilver  belt  of  California  cannot  be  said  to 
be  continuous  to  the  north  of  Clear  Lake,  for  between  that  sheet  of  water 
and  the-  next  deposit  to  the  north  there  is  a  long  stretch  of  country.  It  is 
possible,  indeed,  that  cinnabar  may  yet  be  met  with  in  this  interval,  which 
is  very  inaccessible  and  has  been  but  little  explored.  The  chances,  how- 
ever, seem  against  it,  for  the  volcanic  phenomena  which  are  associated 
with  so  many  of  the  deposits  to  the  south  seem  to  be  absent  between  Clear 
Lake  and  the  neighborhood  of  Mt.  Shasta.  There  are  cinnabar  deposits  at 
the  northern  end  of  the  Coast  Ranges,  however,  in  the  northeastern  corner 
of  Trinity  County,  and  some  fifteen  miles  from  the  edge  of  the  volcanic 
rocks  of  the  Mt.  Shasta  region.  Cinnabar  again  appears  in  the  Cascade 
Ranges  of  Oregon,  which,  as  is  pointed  out  in  Chapter  V,  I  regard  as  a 
northern  continuation  of  the  united  Sierra  Nevada  and  Coast  Ranges  of 
California.  These  occurrences  to  the  north  are  thus  on  a  continuation  of 
the  group  of  profound  dislocations  which  are  marked  by  the  ranges  and 

365 


366  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

deposits  to  the  south,  and  they  show  that  the  series  of  chemical  phenomena 
leading  to  the  deposition  of  cinnabar  have  been  repeated  at  long  geograph- 
ical intervals.  At  the  north,  as  to  the  south  also,  the  deposits  are  formed  at 
no  great  distance  from  lavas.  The  entire  belt  of  country  from  the  mines  of 
Douglas  County,  Oregon,  to  Santa  Barbara  is  thus  structurally  continuous 
and  is  marked  by  irregularly  distributed  volcanic  phenomena  and  cinnabar 
deposits.  In  a  broad  sense  the  entire  zone,  six  hundred  miles  in  length, 
may  be  considered  as  a  quicksilver  belt.  It  will  be  convenient  to  take  up 
the  deposits  not  described  in  the  foregoing  chapters  in  the  order  of  their 
latitude,  beginning  at  the  north. 

North  of  ciear  Lake — The  deposits  of  Douglas  County,  in  Oregon,  are  sit- 
uated on  the  western  flank  of  the  Cascade  Range,  the  base  of  which  is 
composed  of  granite  and  metamorphosed  sandstones  precisely  similar  to 
those  at  Knoxville  and  other  points  to  the  south  which  have  been  minutely 
described  in  Chapter  III.  The  crest  of  the  range  is  occupied  by  lavas. 
The  New  Idrian  mine  is  said  to  be  the  principal  deposit.  It  was  visited  in 
1880  by  Mr.  H.  W.  Leavens  and  it  is  reported  by  him  to  be  a  vein  in  sand- 
stone. The  ore  is  cinnabar  accompanied  by  iron  oxides  and,  according  to 
the  report,  by  manganese  oxide.1  In  1882  fifty  flasks  of  quicksilver  are 
known  to  have  been  produced  by  the  mines  of  this  region. 

Near  the  boundary  between  California  and  Oregon,  in  Del  Norte 
County,  Rockland  district,  in  the  neighborhood  of  the  Diamond  copper 
mine,  cinnabar  and  native  quicksilver  were  described  as  occurring  in  a 
whitish-gray  rock  in  1874.2  I  know  of  no  second  notice  of  this  occur- 
rence. . 

• 

The  quicksilver  district  of  Trinity  County,  California,  is  in  its  north- 
eastern corner.  The  rocks  are  mainly  metamorphosed  sediments,  largely 
serpentinized,  but  volcanic  rocks  are  said  to  occur  at  intervals,  and  there 
are  mineral  springs  directly  at  the  principal  mine,  the  Altoona  (formerly 
called  the  Trinity).  The  rocks  immediately  associated  with  cinnabar  are 
serpentine  and  sandstone.  The  ore  occurs  in  part  as  a  tabular  impregna- 

'  Statistics  and  Technology  of  the  Precious  Metals,  by  S.  F.  Enimous  and  G.  F.  Becker,  pp.  27 
and  28. 

'Mining  ami  Scientific  Press,  vol.  29,  August  15,  1874. 


THE  MANZ  ANITA.  367 

tion  several  feet  in  thickness  and  in  part  as  narrow  seams  of  rich  ore.  One 
observer  describes  the  deposit  as  a  replacement  vein  between  serpentine 
and  sandstone.  The  vein  matter  is  decomposed  country  rock  and  the 
gangue  is  quartz.  The  strike  of  the  deposit  is  nearly  north  and  south.1 

coiusa  county  mines. —  One  of  the  most  interesting  deposits  in  the  world  is 
the  Manzanita  mine,  on  Sulphur  Creek,  close  to  the  hot  sulphur  springs 
now  known  as  Wilbur  Springs,  but  formerly  as  Simmons's  Springs.  The 
rocks  are  highly  metamorphosed  beds  of  the  Knoxville  series.  At  a  dis- 
tance of  about  three-quarters  of  a  mile  from  the  mine  is  a  bed  of  limestone, 
composed  of  shells  of  Rliyncliondla  Whitneyi,  held  together  by  a  small  amount 
of  matrix.  Within  a  few  yards  of  the  mine  itself  I  collected  perfectly  re- 
cognizable specimens  of  Aucella  conccntrica.  The  age  of 'the  rocks  is  thus 
fully  determined.  The  strata  are  thin-bedded,  highly  altered  and  con- 
torted, shaly  sandstones,  a  part  of  them  somewhat  serpentinized.  The 
waters  of  the  hot  springs,  which  are  only  a  few  hundred  feet  from  the  mine, 
are  highly  charged  with  sulphureted  hydrogen  and  are  very  salt.  They 
also  seem  to  contain  borax.  The  surrounding  country  shows  that,  as  is  so 
usual  with  springs  of  this  class,  the  position  of  the  vents  has  repeatedly 
changed  and  much  of  the  rock  in  the  neighborhood  has  been  leached  by 
sulphuric  acid.  Hot  sulphur  waters  once  issued  from  the  mine  itself,  for 
it  contains  a  large  amount  of  free  sulphur.  The  ore  consists  of  cinnabar 
and  gold,  which  are  sometimes  in  direct  contact,  and  some  metacinnabarite. 
These  minerals  are  accompanied  by  pyrite  and  marcasite,  chalcopyrite, 
stibnite,  calcite,  and  quartz.  The  gold  is  often  visible  in  feather-like,  crys- 
talline aggregates,  sometimes  in  direct  contact  with  cinnabar  and  some- 
times deposited  directly  upon  calcite,  which  is  more  prevalent  in  the  ore 
than  is  quartz.  The  cinnabar  and  gold  are  often  separated  by  a  layer  of 
calcite  an  eighth  of  an  inch  in  thickness.  Oily  and  resinous  bitumens  are 
also  tolerably  abundant  in  the  workings. 

The  ores  and  gangue  minerals  do  not  form  a  regular  deposit,  but  occur 
as  thin  seams,  penetrating  the  rock  sometimes  along  the  partings  between 
strata  and  sometimes  cutting  across  the  beds.  It  is  evident  on  inspection 

1  This  information  is  derived  from  an  unpublished  report  of  Mr.  C.  A.  Luckhardt,  Report  of  the 
Mining  Commissioners,  1876,  and  from  Statistics  and  Technology  of  the  Precious  Metals,  by  Emmona 
and  Becker. 


368  QUICKSILVER  DEPOSITS  OF  TOE  PACIFIC  SLOPE. 

that  the  reck  has  been  greatly  disturbed  and  that  wherever  a  fissure  was 
produced  the  ore-bearing  solutions  penetrated. 

The  fact  that  native  sulphur  occurs  in  the  mine  in  considerable  quanti- 
ties, taken  in  connection  with  the  adjacent  springs,  is  sufficient  proof  that 
the  deposit  is  due  to  the  action  of  hot  sulphur  waters.  In  mineralogical 
composition  the  ore  is  similar  to  that  of  most  of  the  quicksilver  mines,  except- 
ing in  the  fact  that  it  carries  gold  in  such  quantities  that  the  mine  has  been 
worked  for  this  metal  As  has  been  seen  in  former  chapters,  gold  occurs 
in  much  smaller  quantities  at  Sulphur  Bank,  Knoxville,  and  Steamboat 
Springs.  The  Manzanita  forms  a  link  between  cinnabar  and  gold  mines 
and  shows  that  both  minerals  may  be  deposited  from  the  same  solutions, 
not  merely  in  traces,  but  in  notable  quantities.  No  volcanic  rock  is  known 
to  exist  within  several  miles  of  the  Manzanita,  but  the  very  hot  sulphur 
springs  seem  ample  evidence  of  volcanic  agencies.  It  is  important  to  note 
that  this  manifestation  of  volcanic  activity  with  attendant  ore  deposition  is 
found  at  a  distance  from  lavas,  so  that,  were  the  springs  to  dry  up  and  the 
country  to  be  somewhat  eroded,  no  direct  evidence  would  remain  that  any 
connection  ever  existed  between  this  deposit  and  the  eruptive  phenomena. 

The  Buckeye  and  the  Abbott's  mines  are  near  the  Manzanita,  and  each 
of  them  has  produced  some  quicksilver,  the  latter  over  two  thousand  flasks. 
Mr.  W.  A.  Goodyear  visited  these  mines.  He  describes  the  ore  as  consist- 
ing of  cinnabar  accompanied  by  pyrite,  marcasite,  and  chalcedonic  silica. 
The  ore  lines  cracks  and  seams  and  impregnates  earthy  matter.  Associated 
with  the  ore  is  a  considerable  quantity  of  the  black  oval  so  often  referred 
to  in  the  preceding  pages.1 

The  Baker  mine. — This  mine  lies  about  half-way  between  Lower  Lake  and 
Knoxville.  It  was  visited  by  Mr.  Goodyear,  who  found  metacinnabarite  in 
the  ores.  A  specimen  of  marcasite  which  I  collected  at  this  mine  was  ex- 
amined for  gold  and  was  found  to  contain  it,  the  quantity  being  about  one 
dollar  per  ton. 

The  Mayacmas  district. —  A  very  large  part  of  the  many  cinnabar  deposits 
north  of  the  Bay  of  San  Francisco  are  found  along  the  Mayacmas  l\ange, 
which  extends  in  a  northwesterly  direction  from  Mt.  St.  Helena.  Two 

1  Geol.  Survey  California,  Geology,  vol.  2,  appendix,  p.  1_M. 


THE  MAYACMAS  BELT. 


369 


of  the  deposits  of  this  district,  the 
Great  Western  and  the  Napa  Consoli- 
dated, have  already  been  described. 
Mr.  Turner  was  instructed  to  make  a 
reconnaissance  of  this  district  as  a 
whole,  and  the  following1  information 
is  chiefly  derived  from  his  report. 

The  underlying  rock  of  the  entire 
district  appears  to  consist  of  metamor- 
phic  strata.  At  the  southeastern  end 
of  the  district  some  of  these  beds 
contain  Aucella  concentrica,  and  are 
certainly,  therefore,  members  of  the 
Knoxville  series.1  The  lithological  and 
physical  character  of  the  metamor- 
phic  rocks  throughout  the  remainder 
of  the  region  is  identical  with  that  of 
the  rocks  immediately  associated  with 
these  fossils  here,  at  Knoxville,  and 
elsewhere,  and  there  is  no  reason  to 
suspect  the  presence  of  strata  of  other 
age  than  the  Neocomian  in  the  met- 
amorphic  series  To  the  north  of  the 
Oathill  mines  is  a  small  area  of  un- 
altered rock  carrying  very  imperfect 
fossils,  the  age  of  which  is  uncertain. 
Upon  the  metamorphic  rocks  lie  great 
quantities  of  andesite  and  basalt.  The 
andesite  is  for  the  most  part  glassy 
when  fresh,  though  asperites  are  al- 
so found.  This  rock  constitutes  the 
greater  part  of  the  mass  of  Mt.  St. 

'The  exact  locality  is  on  (lie  cast  bank  of  Pope 
Creek,  at  the  point  at  which  the  road  from  Lidell  to 
Knoxville  crosses  it. 

MON  XIII ->-! 


370  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Helena  and  covers  large  areas  to  the  north,  east,  and  southeast  of  that 
mountain.  The  summit  of  Mt.  Cobb  is  also  andesitic.  Tufaceous  forms  of 
andesite,  usually  much  decomposed,  are  also  abundant,  especially  to  the 
south. 

At  the  southern  end  of  Mt.  St.  Helena  there  are  argentiferous  quartz 
veins  in  andesite  from  which  a  considerable  amount  of  ore  and,  it  is  said, 
$90,000  of  bullion  have  been  extracted.  About  one  and  a  half  miles  north 
of  Calistoga,  in  King's  Canon  and  on  a  small  ridge  to  the  north  of  it,  there 
are  argentiferous  quartz  veins  in  andesite.  Two  of  these  strike  northeast 
and  southwest  and  two  others  cross  them,  striking  nearly  north  and  south. 
One  of  these  latter  is  called  the  Elephant  and  carries  ore  of  great  interest, 
both  cinnabar  and  pyrargyrite  being  visible  in  it,  as  well  as  pyrite.  Tin- 
cinnabar  was  chemically  tested  and  the  silver  ore  was  analyzed.  The  latter 
contained  antimony,  with  a  mere  trace  of  arsenic,  sulphur,  silver,  copper, 
arid  a  trace  of  lead.  Here,  then,  is  a  true  vein,  carrying  almost  precisely 
the  same  ingredients  as  the  deposits  of  Steamboat  Springs.  This  is  also  the 
only  case  known  as  yet  on  the  Pacific  slope,  excepting  Steamboat  Springs, 
where  lead  and  quicksilver  occur  together.  This  vein  is  certainly  a  com- 
paratively recent  one,  for  the  greater  part  of  the  andesites  of  the  region  are 
Post-Pliocene.  In  ore  from  one  of  the  other  veins  (the  Grigsby)  cinnabar 
and  pyrite  were  found  together. 

Large  quantities  of  basalt  were  erupted  at  a  much  later  period  than 
that  of  the  andesites.  It  occupies  large  areas  to  the  north  of  Oathill  and  the 
igneous  region  east  of  Middletown  is  mostly  basaltic.  Some  of  the  rock 
last  mentioned  produces  a  marked  effect  upon  the  needle  and  contains  much 
magnetite.  In  some  cases  andesitic  hills  are  capped  by  basalt.  There  are 
immense  quantities  of  tufa  to  the  southeast  of  Mt,  St.  Helena,  and  embed- 
ded in  it  are  fragments  of  compact  basalt,  showing  that  the  tufa  belongs  to 
the  basaltic  series  of  eruptions.  The  tufa  is  especially  abundant  in  the 
neighborhood  of  the  North  Cone  and  South  Cone  and  it  often  forms  dis 
tinctbeds,  which  are  sometimes  considerably  inclined.  It  not  infrequently 
includes  great  quantities  of  metamorphic  pebbles. 

The  drainage  and  triangulation  of  the  accompanying  sketch  map  are 
mainlv  compiled  from  surveys  by  Mr.  (J.  F.  Hoffmann,  but  this  material  has 


THE  MAYAOMAS  BELT.  371 

been  supplemented  by  observations  by  Mr.  Turner.  While  the  foregoing 
notes  indicate  in  a  general  way  the  distribution  of  andesite  and  basalt,  no 
attempt  was  made  to  map  the  two  lavas  separately.  The  areas  marked  as 
igneous  are  to  be  considered  as  only  approximately  correct,  the  cartograph- 
ical base  not  being  sufficiently  good  to  permit  of  much  detail.  The  area 
not  occupied  by  igneous  rocks  is  metamorphic. 

The  most  southerly  mine  of  this  district  is  at  Lidell  and  is  known  as 
the  Valley  claim.  Lidell  is  resorted  to  by  invalids  for  the  sake  of  the  hot 
sulphur  baths,  supplied  by  a  spring  which  issues  from  the  old  workings  of 
the  Valley  mine.  Cinnabar  may  still  be  seen  in  the  silicified  and  opaline 
rocks.  The  mine  never  paid  for  working,  but  is  interesting  for  the  direct 
association  which  it  presents  between  cinnabar  and  hot  springs. 

The  ^Etna  property  is  a  mile  distant  from  Lidell  and  comprises  sev- 
eral claims  between  which  are  marked  differences.  The  Phoenix,  which 
has  yielded  large  quantities  of  quicksilver — indeed,  most  of  the  product  of 
Pope  Valley — is  entirely  in  sedimentary  rocks  consisting  mainly  of  serpen- 
tine and  other  highly  metamorphosed  strata,  though  unaltered  sandstones 
also  appear  in  the  workings  and  in  parts  of  the  mine  are  in  direct  contact 
with  the  metalliferous  ground.  The  rock  directly  inclosing  the  ore  from  the 
surface  downward  was  highly  silicified  slate  and  black,  opaline  chalcedony. 
The  cinnabar  occurred  in  stringers  in  this  material  and  as  impregnations 
in  the  softer  rock  and  in  the  attrition  products  accompanying  it.  There  are 
manifold  evidences  of  the  existence  of  a  fissure  system  and  of  motion  in 
the  ground,  so  that  in  some  places  well  defined  walls  exist.  The  ore  was 
first  found  at  the  surface  and  was  followed  down  for  about  one  hundred 
and  fifty  feet.  This  upper  ore  body  yielded  about  seventeen  thousand 
flasks  of  quicksilver  and  then  gave  out  completely.  Vigorous  prospecting 
below  the  old  ore  body  of  late  years  has  disclosed  the  existence  of  more 
oi'C  in  depth.  The  Phoenix  appears  to  belong  to  a  group  of  deposits  of 
cinnabar,  instances  of  which  are  very  numerous.  The  ore-bearing  solu- 
tions have  ascended  along  a  fissure  system,  formed  in  very  heterogeneous 
material,  and  have  penetrated  the  wall  rock  with  corresponding  irregularity, 
producing  irregular  stockworks  and  impregnations  tending  to  a  tabular 
form.  In  the  upper  levels  the  ore  contains  some  native  quicksilver,  which 


372  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

disappeared  as  depth  increased.  Besides  the  usual  pyrite  and  marcasite, 
millerite  is  found  in  fine,  bronze-colored  needles  on  the  300-foot  level.  This 
mineral  has  been  observed  as  microscopic  crystals  in  the  slides  of  ore  from 
several  of  the  mines  in  California,  but  not  elsewhere  in  crystals  visible  to 
the  naked  eye,  so  far  as  I  know. 

Napaute. — The  mine  contains  much  yellow,  bituminous  matter,  usually  of 
a  consistency  similar  to  that  of  shoemaker's  wax;  indeed,  it  has  actually 
been  employed  as  a  substitute  for  that  useful  material.  It  has  been  exam- 
ined by  Dr.  Melville  and  turns  out  to  bo  a  new  mineral. 

The  substance  is  dark  reddish  brown  and  shows  green  fluorescence  by 
reflected  light;  by  transmitted  light,  brilliant  garnet  red.  It  is  interesting 
to  note  that  the  green  fluorescence  disappears  in  a  great  measure  on  ex- 
posure to  the  air,  evidently  with  a  loss  of  some  very  volatile  constituent. 
The  specimens  from  which  the  material  was  obtained  for  analysis  had  un- 
dergone this  change,  only  a  few  smaller  fragments  exhibiting  the  original 
color.  The  ethereal  solution  is  reddish  brown,  with  green  fluorescence,  and 
both  this  solution  and  the  solid  resin  are  highly  refracting.  The  luster  is 
resinous  and  the  hardness  about  2.  Ibis  brittle,  but  by  the  warmth  of  the 
hand  mav  easily  be  molded  and  drawn  into  long  threads.  It  is  not  elastic. 

•/  «/ 

The  fracture  is  conchoidal.  It  begins  to  fuse  at  42°  C.  and  becomes  liquid 
at  46°  C.;  it  boils  above  300°  C.;  at  130°  C.  a  heavy,  colorless  oil  distills 
over,  yielding  an  aromatic  odor ;  then  at  a  higher  temperature  yellow- 
brown  vapors  rise  with  a  peculiar  suffocating  odor,  and  finally  a  heavy, 
dark  red  oil  condenses,  much  resembling  coal-tar  in  smell.  The  boiling- 
point  of  this  last  product  is  not  far  below  the  temperature  of  350°  C. 
Many  intermediate  products  were  obtained  by  fractional  distillation,  but 
the  yield  was  very  small  below  236°  C.,  above  which  colored  distillates 
were  collected.  At  the  temperature  of  softening  of  the  glass  boiling-flask 
a  small  amount  of  carbonaceous  matter  remains,  showing  that  decompo- 
sition in  part  results  Bromine  attacks  the  resin  with  deposition  of  carbon. 
Ether  dissolves  it  completely  in  the  cold;  so,  also,  does  oil  of  turpentine, 
but  not  so  readily;  cold  alcohol  takes  up  but  a  small  quantity.  It  is  com- 
bustible and  yields  absolutely  no  residue.  A  small  amount  of  sulphur  was 
detected  in  one  sample,  but  its  absence  in  others  proved  that  its  origin  was 


V*"  o» 

UJTI7BRSIT7 


373 

in  the  sulphurets  sparingly  disseminated  throughout  the  rock  specimen.  It 
is  associated  with  pyrite  and  millerite  in  vesicular  quartz.  The  specific 
gravity  is  1.02. 

The  following  analyses  were  made  on  three  different  samples  :  (I)  Pure 
material  selected  from  that  in  the  rock  specimen  ;  (II)  material  dissolved  in 
ether  filtered,  and  the  filtrate  allowed  to  solidify  spontaiieously ;  (III)  ma- 
terial fused  at  a  low  temperature  and  allowed  to  flow  away  from  small  frag- 
ments of  rock : 


1- 


II. 


III. 


i 

Carbon,  C 89.84,  f9.54  89.35 

Hydrogen,  H |     10. 1"  |  10.  36  |  10.11 

100.01  99.90  i  99.46 


The  resin  is  therefore  a  hydrocarbon,  and  the  analyses  correspond 
closely  to  the  formula  C3H4,  which  would  contain  90  per  cent,  of  carbon. 
Since  it  is  decomposed  by  heat  its  vapor  density  cannot  be  determined,  and 
its  structural  formula  could  not  be  ascertained  without  a  more  elaborate 
investigation  than  was  practicable.  This  mineral  has  not  been  described, 
and  must  therefore  be  named.  The  term  napalite  seems  unobjectionable. 

On  the  150  and  300/oot  levels  inflammable  gas  issues  from  cracks.  As 
shown  by  the  following  analyses  by  Dr.  Melville,  the  chief  component  is 
marsh  gas : 

Carbonic  uuliydrido 0.74 

Marsh  gas 61.49 

Nitrogen 31.44 

Oxygen G.33 

100. 00 

The  Starr  deposit,  belonging  to  the  same  company,  is  said  to  have 
produced  five  thousand  flasks  of  quicksilver  and  is  of  peculiar  geological 
interest.  It  occurs  at  the  contact  between  a  basalt  dike  and  the  sandstone 
through  which  the  lava  has  broken.  The  ore  occurs  both  in  the  sandstone 
and  in  the  basalt  along  the  contact.  The  workings  extend  to  a  depth  of 
400  feet  from  the  surface  and  the  ore  is  not  yet  exhausted. 

Similar  to  the  last  and  also  on  the  property  of  the  ./Etna  Company  is 
the  Silver  Bow.  So  far  as  observed,  the  ore  in  this  mine  is  wholly  in  the 


374  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPI]. 

decomposed  basalt  close  to  its  contact  with  the  sandstone.  This  dike  is 
typical,  standing  up  as  a  ridge  above  the  inclosing  rocks  and  showing  a 
double  columnar  structure,  one  set  of  columns  being  transversely  arranged, 
while  the  other,  at  the  croppings,  is  nearly  vertical.  The  existence  of  these 
superficial  vertical  columns  shows  that  little  erosion  can  have  taken  place 
since  the  eruption  of  the  rock. 

The  yEtna  property  also  comprises  two  other  claims:  the  Washington, 
containing  alluvial  deposits  of  cinnabar  as  well  as  native  quicksilver  along 
clay  seams,  and  the  Pope  claim,  which  contains  a  deposit  of  cinnabar  in 
contorted  and  silicified  shales.  The  ^Etna  mine  is  included  in  a  belt  com- 
posed of  serpentine,  which  can  be  followed  almost  without  interruption  as 
far  as  St.  Helena  Creek,  a  distance  of  about  seven  miles.  In  this  belt  crop- 
pings  of  opaline  matter,  which  is  largely  opalized  serpentine,  form  an  almost 
continuous  ledge,  with  traces  of  cinnabar  at  many  points.  At  one  point,  the 
No.  2,  or  Phoenix  No.  2,  some  work  has  been  done.  Mr.  Luckhardt  describes 
this  mine  as  opened  upon  a  layer  of  slate  three  to  seven  feet  in  width  and 
carrying  seams  of  ore  of  six  to  eight  inches  in  width.  The  deposit  seemed 
unusually  regular,  but  ore  appears  not  to  have  been  sufficiently  abundant 
to  repay  exploitation. 

All  of  the  deposits  mentioned  above,  as  well  as  the  veins  of  cinnabar 
belonging  to  the  Napa  Consolidated  Company,  which  have  been  described 
in  a  previous  chapter,  are  within  three  miles  of  the  hot  springs  at  Lidell 
and  within  a  triangular  area  measuring  less  than  a  square  mile.  Among 
them  are  deposits  in  unaltered  sandstone,  in  highly  metamorphosed  strata, 
and  in  eruptive  rocks.  The}7  embrace  regular  veins,  impregnations,  and  re- 
ticulated masses.  Three  of  the  deposits  show  unquestionable  connection 
with  very  recent  volcanic  activity,  for  one  of  them  occurs  in  basalt,  the 
second  is  in  contact  with  the  same  lava,  and  a  very  hot  mineral  spring  flows 
from  the  third.  There  is  no  i*eason  to  suppose  that  different  genetic  proc- 
esses have  been  at  work  in  this  small  area;  on  the  contrary,  there  is  every 
reason  to  suppose  that  the  deposits,  embracing  all  the  principal  types  of 
occurrence,  have  been  precipitated  from  waters  heated  by  volcanic  action, 
in  a  manner  similar  to  that  by  which  the  ores  of  Sulphur  Bank  and  Steam, 
boat  Springs  have  been  produced. 


GREAT  EASTERN  AND  GREAT  WESTERN  MINES.  375 

The  next  deposit  to  the  north  of  the  Pope  Valley  group  of  mines  is 
the  Great  Eastern,  in  Lake  County,  on  St.  Helena  Creek.1  This  deposit 
was  remarkable  for  the  richness  of  its  ores,  but  the  quantity  of  quicksilver 
produced  was  small  and  the  mine  has  been  abandoned  for  several  years. 
The  specimens  obtained  from  the  dumps  show  that  the  ore  was  accompanied 
by  opaline  rock  and  that  an  oil  was  present,  associated  with  dolomite.  A 
large  amount  of  unaltered  sandstone  on  the  dumps  suggests  a  wall  of  this 
rock.  Just  northeast  of  this  claim,  on  the  opposite  side  of  the  creek,  is 
Bradford's  Prospect,  in  which  also  the  cinnabar  is  associated  with  opal. 
Difficult  drainage,  due  to  the  proximity  of  the  creek,  is  said  to  have  inter- 
fered with  the  development  of  this  deposit.  It  is  stated  that  since  I  visited 
this  locality  a  shaft  has  been  sunk  and  that  a  considerable  ore  body  has 
been  developed. 

The  next  deposit  to  the  northwest  is  the  Great  Western,  described  in 
detail  in  the  preceding  chapter.  The  district  between  the  Great  Western 
and  Pine  Mountain  has  been  actively  prospected,  and  many  claims  have 
been  taken  up  and  again  abandoned.  It  is  not  possible  to  get  much  infor- 
mation about  these  deposits,  none  of  which  has  been  extensively  developed 
and  in  none  of  which  extensive  ore  bodies  were  found.  The  Wall  Street  is 
on  a  layer  of  opaline,  metamorphic  rock.  Glaucophane  schists  occur  in  this 
mine  and  it  was  in  specimens  from  this  locality  that  glaucophane  was  first 
detected  in  California.  Native  quicksilver  existed  here  as  well  as  cinnabar. 
The  American  mine  was  located  upon  a  ledge  of  indurated  strata  which 
form  croppings  of  considerable  height.  The  rock  consisted  of  alternating 
beds  of  sandstone,  siliceous  slate,  and  partially  serpentinized  sandstone,  and 
underlying  the  ore-bearing  strata  was  dense  serpentine.  The  cinnabar 
sometimes  impregnated  disintegrated  and  ocherous  material,  but  was  mostly 
found  in  seams  and  bunches  in  the  siliceous  rocks.  Quicksilver,  pyrite,  and 
bitumen  accompanied  the  cinnabar.  The  deposit  appears  to  have  been  an 
impregnated  series  of  strata'and  the  ground  must  have  been  charged  with 
ore  after  the  metamorphism  of  the  rock.2  According  to  Mr.  D.  de  Cort;izar3 
specimens  containing  selenide  of  mercury  were  obtained  from  this  mine. 

1  A  more  important  mine  of  the  same  name  in  Sonoiin  Comity  has  been  described  1u  the  preceding 
chapter. 

1  Unpublished  report  of  L.  Janin. 

'British  Reports  on  thr  rhilnrirlpliia  International  Exposition  of  187(1,  vol.  3. 


376  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE 

The  Flagstaff  is  a  claim  adjoining  the  Pioneer  and  very  similar  to  it. 
The  ore-bearing  ground  is  a  stratum  of  argillaceous  sandstone  impregnated 
with  metallic  mercury,  which  is  accompanied  by  a  little  cinnabar.1  Pro- 
fessor Whitney  visited  the  region  in  1861,  when  some  of  the  mines  were 
being  worked,  and  has  published  the  following  notes  concerning  them:2 

The  Cincinnati  is  on  the  bill-side  near  a  steep  canon,  northeast  of  Pine  Mount- 
ain ;  from  it  Mt.  St.  Helena  bears  S.  3^°  E.,  and  tbe  mine  was  estimated  to  have  an 
altitude  of  about  two  thousand  five  hundred  feet.  The  prevailing  rock  is  serpentine, 
filled  with  threads  and  veinlets  of  quartz,  running  through  it  in  every  direction,  pre- 
senting a  rather  peculiar  appearance,  as  some  of  the  quart/  is  in  a  crystallized  form. 
Both  cinnabar  and  native  mercury  have  been  found  here,  but  there  was  little  appear- 
ance of  regularity  in  the  deposit  and  uo  large  mass  of  ore  had  been  discovered.  *  * 

The  Dead  Broke  lies  about  one  mile  west  of  the  Cincinnati.  The  rock  here  con- 
sists of  alternating  layers  of  dark  and  light  colored  and  partly  decomposed  quartzite  ; 
the  strike  is  about  N.  5°  W.-S.  5°  E.,  and  their  dip,  which  is  to  the  west,  about  45°. 
On  the  east  side  of  the  ridge  imperfect  serpentine  was  seen,  and  a  level  had  been 
driven  in  it  for  265  feet.  The  cinnabar,  of  which  rich  specimens  had  been  procured, 
was  contained  in  a  stratum  about  four  inches  wide  and  parallel  with  the  formation. 

The  Pittsburg  claim  is  one  half  a  mile  N.  15°  W.  from  the  Dead  Broke,  and  some 
cinnabar  has  been  found  here  in  serpentine. 

The  Pioneer  mine,  which  is  south  of  Mt,  Cobb  and  not  far  from  the 
Little  Geysers,  was  also  visited  by  Professor  Whitney,  who  says : 

The  rock  most  nearly  associated  with  the  ore  is  the  same  peculiar  siliceous  variety 
usually  seen  at  the  cinnabar  mines  of  California,  and  it  is  inclosed  on  both  sides  by 
serpentine.  The  strike  of  the  metalliferous  lode  or  vein  was  nearly  northwest  and 
southeast.  The  metal  exists  here  both  in  the  form  of  the  sulphuret,  as  cini:abar,  and 
in  the  native  state;  indeed,  so  far  as  we  know,  it  is  one  of  the  most  remarkable  local- 
ities of  native  mercury  ever  discovered.  The  metal  occurs  disseminated  in  fine  glob 
ules  through  the  veiri-stoue,  or  in  larger  quantities  in  the  interior  of  quartz  geodes  or 
pockets.  Over  six  pounds  have  been  saved  from  a  single  pocket,  and  one  of  the  first 
cavities  broken  into  yielded  four  pounds  three  ounces  of  the  metal,  besides  what  was 
unavoidably  lost  in  collecting.  These  facts  are  stated  on  the  authority  of  Mr.  B.  C. 
Wattles,  the  superintendent.  *  *  *  Considerable  bituminous  matter  occurs  here, 
as  in  most  of  the  other  mercury  mines  of  the  State,  and  some  of  the  quartz  geodes 
contain  bitumen. 

From  Pine  Flat,  in-  Sonoma  County,  a  definite  belt  of  deposits  extends 
in  a  direction  which  is  about  25°  west  of  north.  It  is  very  noticeable  on 
the  sketch  map  that  this  belt  of  deposits  occurs  at  a  considerable  distance 
from  any  volcanic  rock,  while,  on  the  other  hand,  it  passes  within  a  mile  of 

'Unpublished  report  by  L.  Juiiin.          3Geol.  Survey  Culiforiiin,  Geology,  vol.  1,  p.  89. 


OAKVILLE  AND  BELLA  UNION  MINES.  377 

the  group  of  hot  sulphur  springs  miscalled  geysers.  Some  of  these  springs 
reach  the  boiling-point  and  emit  steam.  They  are  very  numerous  and  active 
and  are  regarded  as  one  of  the  sights  of  California.  Their  character  is  such 
as  is  almost  universally  attributed  to  volcanic  activity.  Their  presence  near 
the  quicksilver  mines  therefore  indicates  that  the  remoteness  of  the  deposits 
of  cinnabar  from  the  nearest  lavas  does  not  preclude  a  relation  between  vol- 
canic activity  and  ore  deposition.  The  mines  of  this  group  are  the  Sonoma, 
the  Rattlesnake,  the  Little  Missouri,  the  Oakland,  the  Kentucky,  and  the 
Cloverdale.  The  Rattlesnake  produced  only  about  sixty-five  flasks  of  quick- 
silver, but  it  is  a  noteworthy  fact  that  this  product  was  obtained  almost 
entirely  from  native  quicksilver  disseminated  in  a  friable  sandstone.  An 
unusual  quantity  of  oily  bitumen  accompanied  this  ore,  and  it  is  recorded 
that  there  were  special  arrangements  to  burn  the  hydrocarbons  because  of 
the  quantity  of  soot  which  they  formed  in  the  condensers.1  Though  most 
of  the  ore  was  an  impregnated  unindurated  sandstone,  the  usual  opaline 
rock  also  occurred  here  and  sometimes  showed  geodes  containing  oil.  The 
Oakland  mine,  as  stated  in  the  table  of  production,  Chapter  I,  produced 
G,831  flasks,  and  may  perhaps  be  reopened  under  favorable  circumstances 
The  product  of  the  Cloverdale  was  2,GG1  flasks,  but  the  Kentucky  only 
turned  out  54  flasks.  Another  small  mine,  beyond  the  limits  of  the  map, 
is  the  Livermore.  It  lies  two  miles  west  of  the  junction  of  Pluton  Creek 
and  Sulphur  Creek. 

oakviiie  ana  Beiu  union. —  Small  quantities  of  cinnabar  occur  in  the  hills 
bounding  Napa  Valley  on  the  west,  about  half  way  between  Calistoga  and 
Napa  City.  The  principal  deposits  are  on  two  adjoining  claims,  the  Bella 
Union  and  the  Oakviiie.  The  rock  is  siliceous  slate,  associated  with  serpen- 
tine. The  slates  strike  north  and  south  and  dip  at  60°  or  70°  westward 
toward  the  summit  of  the  range.  The  ore  is  exclusively  cinnabar,  accom- 
panied by  pyrite  and  calcite.  It  forms  seams  in  the  slates  and  irregular 

o 

bunches  connected  by  narrow  stringers  of  ore.  The  Bella  Union  has  pro- 
duced some  metal.2 


T.  Egleston,  Trans.  Am.  Inst.  Min.  Eng.,  vol.  3,  p.  273. 

8  The  information  concerning  these  mines  is  derived  from  an  unpublished  report  of  Mr.  C.  A.  Luck- 
hardt. 


378  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


county.  —  The  most  southerly  of  the  mines  north  of  tlie  Bay  of  San 
Francisco  is  the  St.  John's,  four  miles  northeast  of  Vallejo.  It  is  situated  in 
an  isolated  ridge  of  metnmorphic  rock  trending  from  northwest  to  southeast 
and  lying  in  Sulphur  Spring  Valley.  The  surrounding  region  is  unaltered. 
In  the  metamorphic  area  also  there  are  portions  of  little  modified  rock,  and 
at  two  points  on  the  ridge  Mr.  Turner  found  Aucclla  moxquensis.  One  of 
these  localities  is  in  the  main  tunnel  of  the  St.  John's  mine,  and  the  shales 
in  which  the  fossils  occur  seem  beyond  doubt  the  same  which,  at  a  distance 
of  150  feet  from  the  fossils,  are  indurated  and  contain  cinnabar.  The 
second  Aucclla  locality  is  three-quarters  of  a  mile  southeast  of  the  mine  on 
the  same  ridge.  At  this  point  the  shells  occur  in  calcareous  nodules  in 
shale.  These  fossils  of  course  determine  the  rocks  as  belonging  to  the  Neo- 
comian  formation. 

The  ore  was  found  at  the  croppings  and  is  said  to  have  been  discovered 
as  early  as  1852.  The  ore  body  exposed  at  the  croppings  extended  down- 
ward about  four  hundred  feet  and  furnished  most  of  the  metal  which  this 
mine  has  produced.  Much  of  this  ore  was  inclosed  in  a  white,  greatly 
decomposed  rock,  which  is  probably  a  metamorphosed  sediment,  further 
altered  by  the  action  of  sulphuric  acid  and  other  reagents.  At  one  point  it 
crosses  the  tunnel  very  like  a  dike.  There  is  nothing  suggesting  the  pres- 
ence of  eruptive  rocks  on  the  surface.  According  to  Mr.  Neate,  the  owner 
of  the  property,  an  open  fissure  exists  in  proximity  to  the  main  ore  body, 
but  the  position  of  this  fissure  is  now  inaccessible.  Like  most  of  the  quick- 
silver mines,  the  St.  John's  carried  some  bituminous  matter.  In  the  west- 
ern mine  workings  cinnabar  occurs  in  highly  siliceous,  apparently  chalce- 
donic  rocks,  and  close  by  is  serpentine,  forming  a  wall  to.  the  ore-bearing 
ground.  As  appears  from  the  table  of  production,  this  mine  has  yielded 
8,598  flasks  of  metal. 

MI.  Diablo.  —  Cinnabar  is  found  on  the  eastern  slope  of  the  north  peak  of 
Mt.  Diablo,  associated  with  the  usual  black  opal  and  chromic  iron  ore.  It 
is  said  that  some  thousands  of  dollars'  worth  of  the  metal  was  extracted 
from  this  locality.  In  the  ravine  just  below  the  mine  is  a  sulphur  spring,  and 
farther  down  the  slope  is  another  mineral  spring  which  must  formerly  have 
been  very  active,  for  it  has  deposited  a  large  quantity  of  calcareous  sinter. 


PANOCHK  DISTRICT.  379 

To  the  south  of  this  spring  deposit  in  a  hill  of  asperite  and  at  the  con- 
tact between  this  lava  and  the  unaltered  shale  Mr.  Turner  found  cinnabar. 
It  is  associated  with  copper  pyrites  and  calcite  and  in  some  cases  is  so  in- 
termingled with  the  latter  as  to  show  simultaneous  deposition.  There  seems 
to  be  no  quartz  or  opal  at  this  point.  This  is  the  third  locality  in  California 
at  which  cinnabar  is  found  associated  with  andesite,  and  the  circumstances 
are  such  as  to  leave  little  or  no  doubt  that  the  deposition  took  place  from 
hot  sulphur  springs,  induced  by  volcanic  action. 

Traces  of  cinnabar — The  discovery  of  cinnabar  at  Point  Reyes  was  reported 
in  187;").'  There  is  no  improbability  in  the  statement,  but  I  have  heard  of 
no  confirmation  of  the  report  and  hesitate  to  enter  it  on  the  map.  Pro- 
fessor Whitney  states  that  small  quantities  of  cinnabar  and  mercury  were 
found  in  early  days  near  the  Mission,  in  San  Francisco,  in  rocks  of  the 
usual  type. 

Santa  clara  county. — Besides  the  New  Almaden,  Euriquita,  and  Guadalupe, 
which  form  the  subject  for  Chapter  X,  a  small  mine  called  the  San  Juan 
Bautista  was  worked  in  former  years.  It  is  in  the  northeastern  portion  of 
an  isolated  range  or  cluster  of  hills  bearing  the  same  name  and  is  about 
four  miles  southeast  of  San  Jose.  The  hills  are  composed  of  metamorphic 
rocks,  largely  serpentine.  The  ore  deposits  were  irregular,  but  seemed  in 
a  general  way  to  follow  the  stratification.  Mr.  Goodyear  (loc.  cit.)  notes 
the  presence  of  chalcedonic  silica  and  of  a  hard,  dark-gray,  granular,  crys- 
talline rock,  which  was  probably  pseudodiabase.  My  party  has  not  visited 
this  deposit 

panoche  district — Paiioche  Pass,  which  is  near  the  junction  of  Fresno, 
Merced,  and  San  Benito  Counties,  leads  from  the  area  drained  by  the 
Pajaro  River  to  that  drained  by  the  San  Joaquin.  The  divide  forms  a  por- 
tion of  the  somewhat  irregular  mountain  system  called  by  Professor  Whit- 
ney the  Mt.  Diablo  Range  and  is  composed  of  rocks  identical  in  character 
with  the  central  metamorphic  mass  of  Mt.  Diablo.  There  is  no  reason  for 
supposing  these  rocks  to  be  of  different  age  from  those  of  Mt.  Diablo  and 
Knoxville,  and  there  is  considerable  evidence  that  like  them  they  are  Neo- 
comian,  but  no  fossils  were  found  in  them.  The  surrounding  country  con- 

1  Mining  and  Scientific  Press,  February  27,  1875. 


380  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC!  SLOPE. 

tains  Miocene  sandstones  and  heavy  gravels  supposed  to  be  Pliocene. 
Both  of  these  formations  have  been  greatly  disturbed  and  often  stand  at 
high  angles.  The  metamorphic  rocks  near  Panoche  Pass  contain  a  number 
of  deposits  of  quicksilver,  some  of  which  have  yielded  metal. 

The  Stayton  mines  was  the  name  given  to  a  group  of  fourteen  prospects, 
which  are  remarkable  because  they  contain  stibnite  in  quantities  equal  to  or 
greater  than  those  of  cinnabar.  At  one  time  quicksilver  was  reduced  in  a 
retort  at  this  locality  and  at  another  the  antimony  ore  was  smelted.  The 
mines  have  not  been  in  operation  for  some  years  and  little  could  be  seen  at 
the  time  of  my  visit,  excepting  that  both  minerals  occurred  in  proximity, 
chiefly  with  quartz  gangue,  in  siliceous  and  serpentinized  rocks  of  the  usual 
type.  I  saw  no  indications  of  a  large  or  a  regular  deposit.  The  Wonder 
quicksilver  mine  was  close  to  the  Stayton  and  is  said  to  have  been  similar. 

About  eleven  miles  west  of  Panoche  post-office,  near  the  main  high  road, 
is  a  prospect  called  the  Cerro  Gordo.  It  is  remarkable  for  the  presence  of 
metacinnabarite  in  the  ore,  which  contains,  besides,  cinnabar,  pyrite,  and 
bitumen,  associated  with  opal  and  crystalline  silica.  The  inclosing  rocks 
are  of  the  metamorphic  series  and  contain  titaniferous  magnetite.  The 
material  on  the  dumps  seemed  to  me  of  a  promising  character. 

The  Little  Panoche  mine  is  in  a  canon  at  the  north  end  of  Little  Pano- 
che Valley.  The  workings  were  never  large  and  are  now  for  the  most  part 
inaccessible.  The  rock  is  metamorphic  sandstone,  highly  silicified,  but  ac- 
companied by  only  trifling  quantities  of  serpentine.  The  ore,  as  shown  by 
the  dumps,  consisted  of  cinnabar  and  pyrite  in  a  quartz  gangue,  with  meta- 
morphic sandstone.  I  saw  no  evidence  of  a  defined  vein,  though  the  work- 
ings may  have  disclosed  something  of  the  sort. 

The  Cerro  Bonito,  sometimes  called  the  Panoche  Grande,  is  about 
three  miles  by  road  from  Panoche  post-office,  in  the  northwestern  corner 
of  Fresno  County.  It  lies  close  to  a  basalt  area  of  considerable  size,  the 
only  one  of  the  kind  known  to  me  in  this  part  of  the  country.  The  mine 
is  in  metamorphic  sandstone,  accompanied  by  serpentine,  and  the  ore  is 
associated  with  quartz  and  calcite.  Very  little  pyrite  exists  in  the  dumps 
and  the  ore  was  dull,  unpromising-looking  material.  According  to  Mr.  L. 
Janin,  the  ore  followed  the  stratification.  The  most  promising  ore-bearing 


SAN  LUIS  OBISPO  DISTRICT.  381 

ground  was  a  vein-like  formation  from  two  to  five  feet  in  width,  consisting 
of  earthy  decomposed  rock,  in  which  occurred  threads  and  bunches  of  cin- 
nabar. Bowlders,  too,  were  included  in  the  matrix;  they  were  impregnated 
with  cinnabar  to  a  greater  or  less  extent. 

san  Luis  obispo. — The  mines  of  the  San  Luis  Obispo  are  on  the  Santa  Lucia 
Range,  which  extends  from  near  Monterey  southward  along  the  coast. 
TUs  range  is  chiefly  composed  of  metamorphic  rocks  and  Miocene  beds. 
The  metamorphic  rocks  are  lithologically  identical  with  those  farther  north 
and  are  also  of  the  same  age.  Five  miles  from  the  town  of  San  Luis 
Obispo,  on  the  road  to  Santa  Margarita,  in  a  patch  of  comparatively  little 
altered  shale  inclosed  in  the  metamorphic  series,  Mr.  Turner  found  an  ex- 
cellent specimen  of  AuceUa  mosquensis.  This  is  the  most  southerly  locality 
at  which  this  characteristic  fossil  of  the  Knoxville  series  has  been  encoun- 
tered, and  it  is  nearly  three  hundred  miles  in  a  direct  line  from  the  Man- 
zanita  mine,  in  Colusa  County,  where  AuceUa  was  also  found.  This  inter- 
val is  equal  to  three-fifths  of  the  entire  length  of  the  Coast  Ranges  from 
Ft.  Tejon  to  Shasta  City. 

There  is  a  considerable  extent  of  Miocene  rocks  in  this  region,  as  well 
as  a  volcanic  range  which  trends  in  a  westerly  direction  and  ends,  according 
to  Professor  Whitney,  in  the  Moro  rock  off  the  coast.  It  seems  to  consist 
of  asperites.  Hot  springs  are  said  to  exist  in  abundance  in  the  quicksilver 
district  of  San  Luis  Obispo,  and  extinct  springs,  evidently  similar  to  those 
now  active,  are  stated  to  occur  close  to  the  most  productive  of  the  mines, 
the  Oceanic.  The  hot  sulphur  springs  of  Paso  Robles  are  not  far  from 
this  group  of  mines. 

The  Rinconada  mine  is  sunk  on  a  deposit  in  metamorphic  rocks  among 
which  is  serpentine.  These  rocks  are  not  distinguishable  from  those  at 
New  Almaden  and  other  more  northern  districts.  The  deposit  is  partly  in 
slaty  material,  accompanied  by  black  opal,  and  partly  in  indurated  sand- 
stones. Pyrite,  calcite,  dolomite,  quartz,  and  organic  matter  accompany 
the  ore.  It  is  to  some  extent  disseminated,  but  usually  occupies  cracks  in 
the  rocks,  which  it  often  only  partially  fills.  The  crevices  sometimes  cross 
the  beds  and  sometimes  follow  them.  The  deposit  has  not  as  yet  proved  of 
any  commercial  value.  It  is  interesting  because  its  general  character  is  so 


382  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

like  that  of  many  deposits  to  the  north  in  mineral  association,  in  structure, 
and  in  the  age  of  the  inclosing  rocks. 

Judging  from  reports  of  Mr.  Janin,  the  Ocean  View,  Keystone,  Jose- 
phine (also  called  Sunderland  and  Luckhardt),  and  other  mines  seem  to 
have  been  essentially  similar  in  the  mode  of  their  occurrence  to  the  Rin- 
conada  and  to  a  great  proportion  of  the  other  quicksilver  deposits  of  Cali- 
fornia. The  Oceanic  was  more  exceptional,  for  its  deposit  consisted  of  a 
stratum  of  unaltered  sandstone  impregnated  with  cinnabar.  The  width  of 
the  stratum  was  several  yards  and  at  one  time  the  entire  body  of  rock  paid 
for  extraction  and  reduction.  Specimens  show  that  the  cinnabar  is  asso- 
ciated with  quartz  as  a  gangue  and  that  stringers  of  ore  and  gangue  as  well 
as  impregnations  occurred.  A  coarse  conglomerate,  said  to  form  the  "  cas- 
ing of  the  vein,"  contains  metamorphic  pebbles,  showing  that  the  rock  is  at 
least  as  late  as  the  Chico  and  probably  Miocene,  but  no  fossils  are  known 
to  have  been  found  in  it,  There  is  nothing  improbable  in  the  hypothesis 
that  this  rock  is  Tertiary  ;  for  it  has  been  shown  in  this  report  that  in  Cali- 
fornia cinnabar  is  associated  with  many  rocks,  both  Pre-Miocene  and  Post- 
Miocene,  and  that  it  is  known  to  exist  in  Tertiary  strata  in  other  parts  of 
the  world.  The  appearance  of  one  specimen  from  the  Oceanic  suggests 
that  the  works  have  struck  metamorphic  rock  beneath  the  sandstone.  The 
Sulphur  Spring  claim  adjoining  the  Oceanic  on  the  west  yields  specimens  of 
rich  cinnabar.  In  the  northwest  portion  of  San  Luis  Obispo  County  good 
ore  occurs  at  the  Polar  Star  mine. 

Santa  Barbara — The  Los  Prietos  is  on  the  northern  flank  of  the  Santa  Inez 
Range,  some  five  miles  northerly  from  the  town  of  Santa  Barbara.  A  belt 
of  quicksilver-bearing  rock  is  said  to  extend  from  this  point  for  about  six 
miles  on  a  course  south  50°  east,  or  approximately  in  the  direction  of  the 
range,  and  upon  it  several  claims  have  been  located.  The  occurrence  is  of 
the  usual  kind  —  seams  and  bunches  of  cinnabar  in  metamorphic  rocks, 
including  serpentine  and  serpentinoid  rocks.  Specimens  also  show  light- 
colored  limestone  with  cinnabar.  These  mines  have  turned  out  a  small 
quantity  of  ore,  some  of  which  has  been  reduced.1  Hot  springs  occur  at 
several  points  along  this  range  of  mountains. 

'This  information  is  derived  from  Mr.  Janin. 


QUICKSILVER  ON  THE  GOLD  BELT.  383 

other  traces  ot  dnnabar. — The  occurrence  of  traces  of  quicksilver  has  been  re- 
ported a  number  of  times  near  Lake  Elizabeth,  in  Los  Angeles  County,  and 
the  report  is  credited  by  persons  whose  opinion  is  entitled  to  respect.  Cin- 
nabar also  occurred  near  San  Bernardinor  -A  small  deposit  is  said  to  have 
worked  out  long  since,  and  new  discoveries  were  announced  in  1873. 1 

According  to  Mr.  Schmitz,  a  mine  superintendent,  gold  amalgam  was 
found  at  many  points  on  the  gold  belt  in  early  days.  He  found  one  occur- 
rence in  stringers  in  ''greenstone"  five  feet  below  the  surface,  which  was 
analyzed  by  Sonnenscheitr  and  gave  the  formula  AuIIg3.  The  exact  locality 
is  not  given. 

Three  extremely  interesting  occurrences  on  the  gold  belt  of  California 
are  described  by  Professor  Whitney.  One  of  these  is  in  Mariposa  County, 
on  the  north  bank  of  the  Merced  River,  near  Horseshoe  Bend.  Here  an 
auriferous  quartz  vein  six  inches  wide  and  resembling  other  such  veins  in 
most  respects  carried  on  its  foot-wall  a  thin  seam  of  quartz  containing  cin- 
nabar in  crystalline  plates  and  bunches.  The  seam  was  about  an  inch  wide 
and  appeared  to  be  continuous.3 

Mr.  C.  L.  Mast  is  now  the  owner  of  a  ledge  on  the  hillside  east  of  the 
Merced  River,  near  the  mouth  of  Maxwell  Creek,  not  far  from  Coulterville, 
which  is  probably  the  same  vein  referred  to  by  Professor  Whitney.  The 
country  rock  is  of  the  kind  called  by  Professor  Whitney  greenstone  and 
by  Professor  Wadsworth  diabase  tufa.  The  cinnabar  occurs  in  crystals  of 
unusually  large  size  embedded  in  quartz  and  accompanied  by  very  little 
pyrite.  This  ore  was  sold  to  the  Chinese  between  1850  and  I860.  Mr. 
J.  W.  C.  Maxwell  informs  me  that  many  years  ago  extraordinarily  well 
crystallized  cinnabar  in  a  quartz  gangue  used  to  be  brought  from  the  country 
back  of  the  town  of  Merced  and  sold  to  the  Chinese  as  vermilion  at  a  hi»-h 

O 

price  per  ounce.  This  cinnabar  may  have  come  from  the  vein  just  described 
or  possibly  from  some  similar  locality  now  unknown.  In  Calaveras  County, 
near  Murphy's,  a  quartz  vein  assaying  well  for  gold  also  carried  cinnabar  in 
small  quantities,  according  to  Professor  Whitney,  with  traces  of  vitreous 
copper  ore  and  copper  carbonates.  The  same  geologist  has  also  seen  speci- 

1  Mining  and  Scientific  Press,  vol.  27,  187:!,  p.  1GG. 
"Zeitschr.  Dnilscli.  gcol.  (icsell.,  vol.  C>,  1854,  p.  24;!. 
"Geol.  Survey  California,  Geology,  vol.  1,  p.  2;iO. 


384  QUICKSILVER  DEPOSITS  OF  TBE  PACIFIC  SLOPE. 

mens  of  gravel  from  near  Placerville,  El  Dorado  County,  containing  gold 
and  rounded  grains  of  pure  cinnabar.1  This  is  probably  at  or  near  the 
locality,  three  miles  south  of  Shingle  Springs,  from  which  not  only  float  cin- 
nabar, but  a  ledge  carrying  this  ore,  was  reported  some  years  since.2 

Mr.  Turner  has  visited  this  locality,  which  is  at  Cinnabar  City.  The 
deposit  is  a  bedded  vein  in  slates  and  quartzitic  rocks.  The  cinnabar, 
accompanied  by  pyrite,  occupies  interstitial  spaces.  A  furnace  was  built 
here  and  some  quicksilver  was  produced.  According  to  the  county  sur- 
veyor, Mr.  G.  W.  Kemble,  cinnabar  also  occurs  in  place  in  the  ravine  of 
Hastings  Creek  near  its  mouth  and  in  the  ravine  of  Clark's  Creek  about 
one  mile  from  its  mouth,  the  two  localities  being  presumably  on  the  same 
ledge.  Hastings  Creek  empties  into  the  south  fork  of  the  American  River 
from  the  north  about  three  miles  from  Coloma.  Clark's  Creek  flows  from 
the  south  into  the  same  river  about  four  miles  northwest  of  Coloma. 

Gold  amalgam  is  reported  from  British  Columbia.3  Mr.  H.  G.  Hanks 
has  also  analyzed  arquerite  (silver  amalgam)  from  Vital  Creek,  British 
Columbia,  in  latitude  53°  north.4 

The  only  cinnabar  deposit  in  British  Columbia  upon  which  any  work 
has  been  done  is  at  Kicking  Horse  Pass  (lat.  51°  20',  long.  116°  30'),  two 
and  a  half  miles  east  of  Garden  City.  It  is  called  the  Ebenezer  and  is 
described  as  a  vein  of  calcite  flecked  with  grains  of  cinnabar.  The  ore  is 
accompanied  by  pyrite  and  contains  traces  of  gold.5  Dr.  G.  M.  Dawson 
reports  that  float  cinnabar  has  been  found  in  the  gold  washings  on  the 
Eraser  River,  near  Boston  Bar.  Rich  specimens  containing  cinnabar  and 
native  metal  are  said  to  have  come  from  the  west  side  of  the  Eraser,  near 
Clinton,  and  the  silver  ores  from  Hope,  on  the  Eraser,  are  stated  to  contain 
mercury.  A  well  denned  lode  containing  rich  cinnabar  ore  is  also  said  to 
occur  on  the  Homathco  River.6 

Mr.  W.  H.  Dall  informs  me  that  in  1865  he  saw  a  large  piece  of  cin- 
nabar in  the  Colonial  Museum  at  Sitka,  Alaska,  which  was  said  to  have  been 

1  Auriferous  Gravels,  p.  367. 

^Mining  .and  Scientific  Press,  vol.  31,  1875,  p.  118. 

3GeoI.  Survey  Canada,  Geol.  Canada,  18G3,  p.  518. 

*  Kept.  State  mineralogist  California,  vol.  4,  1884,  p.  12. 

"Ann.  Kept.  Geol.  Survey  Canada,  18*ti,  pp.  !>  T  and  40  D. 

6 Kept.  Progress  Geol.  Survey  Canada,  l-7i'-'?7,  p.  l:!;i. 


QUICKSILVEE  DEPOSITS  IN  THE  GREAT  BASIN".  385 

brought  in  by  the  Indians  from  some  portion  of  the  Alexander  Archipelago. 
It  has  since  been  reported  as  occurring  on  the  Kuskokwim  River.  There 
seems  to  me  no  reason  to  doubt  that  cinnabar  really  does  occur  in  Alaska, 
though  more  definite  information  is  to  fee-desired. 

In  the  Great  Basin  quicksilver  ores  occur  at  several  points  besides 
Steamboat  Springs.  In  Idaho  considerable  quantities  of  float  cinnabar 
have  been  found  in  Stanley  Basin,  at  the  eastern  extremity  of  Boise"  County, 
and  along  the  Salmon  River  between  the  mouth  of  Yankee  Fork  and  the 
town  of  Sawtooth,  but  the  ore  has  not  been  found  in  place.1 

Prof.  W.  P.  Blake  wrote  in  18»i7:2 

Ciunabar  of  a  beautiful  vermilion  color  is  fouud  in  Idaho  abundantly  spread 
through  a  gaugue  of  massive  compact  limestone  or  marble.  No  quartz  or  other  minerals 
are  visible  in  the  specimens. 

Professor  Blake  writes  me  that  these  specimens  were  water  worn  or 
rounded  fragments  about  the  size  of  one's  fist,  and  he  thinks  it  not  im- 
probable that  the}-  formed  portions  of  a  calcite  vein  in  some  other  rock. 
Judging  from  the  frequent  occurrence  of  cinnabar  with  calcite  in  fissures 
in  many  parts  of  the  world,  this  also  appears  to  me  probable.  He  cannot 
recollect  ever  having  been  informed  as  to  the  precise  locality  from  which 
the  specimens  came,  and  they  are  most  likely  therefore  to  have  been  found 
in  one  or  the  other  of  the  regions  referred  to  above.  Cinnabar,  then,  so 
far  as  known,  has  never  been  found  in  place  in  Idaho. 

Mr.  Janin  informs  me  of  a  very  interesting  occurrence  of  cinnabar  in 
the  Belmont  district,  Nevada.  Rich  seams  of  nearly  pure  cinnabar  were 
found  here  in  the  Barcelona  silver  mine,  following  along  the  vein  of  argen- 
tiferous ore.  Cinnabar  has  also  been  reported  from  Humboldt  County  and 
from  the  southeastern  corner  of  Nevada,  but  with  no  details  as  to  occurrence. 

In  Utah  the  Lucky  Boy  claim,  Mt.  Baldy  district,  Piute  County,  con- 
tains bunches  of  tiemannite  (mercuric  selenide)  in  limestone.3  In  Feb- 
ruary, 1887,  a  mine  was  at  work  in  the  Lucky  Boy  claim  upon  a  body  of 
this  rare  ore  about  four  feet  in  thickness.  The  ore  sometimes  contains  70 
per  cent,  of  mercury  and  is  said  to  average  10  per  cent.  Three  retorts 
were  running  and  producing  enough  quicksilver  to  pay  expenses.  The 

1  Kininous  and  Hecker,  op.  cit.,  p.  55.  •'Emnions  and  Becker,  loc.  cit.,  p.  463. 

2  Am.  Jour.  Sci.,  2d  sciies,  vol.  4:?,  1867,  p.  125. 

MON  XIII L'u 


386  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

product  for  the  last  quarter  of  188G  was  87  flasks.  A  furnace  was  being 
built.1  This  is,  I  believe,  the  only  case  in  which  tiemannite  has  ever  been 
mined  and  reduced  on  a  commercial  scale.  A  body  of  low-grade  cinna- 
bar is  said  to  have  been  found  near  this  mine.  I  also  learned  from  Mr.  J. 
E.  Clayton,  through  Mr.  D.  T.  Day,  that  cinnabar  is  found  in  the  Camp 
Floyd  district,  near  Lewiston,  in  the  Oquirrh  If jinge,  about  sixty  miles  south- 
west of  Salt  Lake  City.  The  ore  is  said  to  occur  in  bunches  and  seams  in 
calcareous  shales  of  Carboniferous  age  and  to  be  accompanied  by  heavy 
spar.  The  deposits  at  this  locality  can  be  followed  for  a  mile  or  more,  but 
the  ore  is  of  low  grade  and  has  not  been  worked. 

Cinnabar  has  been  reported  from  New  Mexico,  but  I  have  seen  no 
definite  locality  given  and  no  particulars.  Many  years  since,  remarkable 
specimens  of  ore  containing  cinnabar  with  gold,  silver,  and  copper  ores 
were  shown  in  San  Francisco,  which  it  was  said  came  from  Arizona. 


1  This  iuformatiou  was  obtained  from  Mr.  P.  Cope,  general  freight  ageut  of  the  Utah  Central  Kail- 
way. 


CHAPTER  XIV. 

DISCUSSION  OF  THE  ORE   DEPOSITS. 

Purpose  of  the  chapter.  — The  various  cinnabar  deposits  of  the  Pacific  slope 
have  many  features  in  common ;  indeed,  it  does  not  appear  to  me  practi- 
cable to  divide  them  into  two  or  more  groups.  Each  mine,  however,  affords 
special  facilities  for  the  study  of  particular  characteristics  and  comparisons 
are  essential.  This  chapter  will  be  devoted  to  comparative  descriptions  of 
the  deposits  and  I  shall  also  endeavor  to  include  in  it  such  information  with 
reference  to  the  occurrences  as  seems  likely  to  be  welcome  to  readers  who 
desire  a  general  knowledge  of  the  quicksilver  deposits  of  the  Pacific  slope 
rather  than  full  particulars  of  any  one  property.  It  will  include  studies 
of  the  ores,  gangue  minerals,  and  inclosing  rocks,  a  discussion  of  the  place 
which  these  ore  bodies  occupy  in  the  general  classification  of  deposits,  and 
remarks  on  the  relations  which  they  bear  to  metamorphic  areas  and  to 
volcanic  rocks.  The  origin  of  the  ores  and  the  manner  in  which  they  were 
dissolved  and  precipitated  will  be  discussed  in  separate  chapters. 

MINERALOGICAL    CHARACTER    OF    THE    DEPOSITS. 

ores. —  Quicksilver  is  obtained  on  the  Pacific  slope  from  four  minerals, 
cinnabar,  metacinimbarite,  native  quicksilver,  and  tiemannite  (mercuric  sel- 
enide).  The  last  occurs  in  quantity  only  near  Marysville,  Piute  County, 
Utah.  Reduction  works  are  in  operation,  and,  it  is  said,  at  a  profit.  Cin- 
nabar is  the  chief  ore  in  the  United  States,  as  it  is  elsewhere,  and  only  a 
small  portion  of  the  metal  is  obtained  from  mctacinnabarite  or  in  the  native 
state.  In  the  Kedington,  Reed,  and  New  Idria  mines,  however,  large  quan- 
tities of  metacinnabarite  were  obtained  from  the  higher  levels,  but  large 
masses  of  this  ore  have  not  been  seen  in  place  during  the  present  investiga- 

387 


I 


388  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

tion.  Native  quicksilver  in  small  and  variable  quantities  is  met  in  many  of 
the  mines.  It  is  naturally  oftener  found  in  the  lower  portions  of  ore  bodies 
than  elsewhere,  because  of  its  fluidity  and  its  high  specific  gravity,  just  as 
it  permeates  the  earth  far  below  the  foundations  of  reduction  furnaces  when 
special  means  are  not  adopted  to  obviate  its  percolation.  Hence  miners  do 
not  welcome  the  appearance  of  native  quicksilver. 

Gangue  minerals. —  Dense  masses  of  cinnabar,  of  considerable  size,  are  found 
in  most  ore  bodies,  but  the  larger  part  of  the  ore  is  mingled  with  gangue 
minerals.  These  are  few  in  number  and  are  substantially  the  same  in  all 
the  deposits.  They  are  crystalline  silica,  opal,  calcite,  and  dolomite.  Asso- 
ciated with  the  cinnabar  is  also  invariably  pyrite  or  marcasite  (sometimes 
slightly  auriferous):  millerite,  too,  in  small  quantities  is  common;  and  traces 
of  copper  as  sulphide  or  carbonate  are  occasionally  seen.  Bituminous  mat- 
ter is  present  in  all  the  mines  examined  excepting  Steamboat  Springs.  This 
substance,  though  sometimes  disseminated  through  ore,  is  usually  found  in 
spots  in  the  country  rock.  Sulphur  occurs  at  the  surface  of  three  of  the 
most  recent  deposits,  and  in  the  Maozanita  mine,  Colusa  County,  native  gold 
and  cinnabar  are  mingled.  Cinnabar  is  also  met  with  in  some  of  the  gold 
quartz  veins  of  the  gold  belt.  1'yrargyrite  and  cinnabar  are  associated  near 
Calistoga  and  this  ore  also  contains  arsenic  and  lead.  At  the  Barcelona  silver 
mine  in  Nevada  cinnabar  was  found.  A  mixture  of  cinnabar  with  gold,  silver, 
and  copper  ores  is  reported  from  Arizona,  and  at  Steamboat  the  deposits  con- 
tain gold,  silver,  lead,  copper,  arid  zinc  I  know  of  no  other  case  on  the 
Pacific  slope  where  zinc  is  found  with  quicksilver,  but  this  association  is  not 
unknown  in  Europe.  .The  bitumen  posepnyte  was  recognized  at  the  Great 
Western  mine  and  a  new  bituminous  mineral,  christened  n«j>ulilc,  was  found 
at  the  Phoenix  mine. 

other  associated  minerals. — Various  other  minerals  have  been  identified  in 
the  mines,  less  important  than  the  above  or  less  closely  associated  with  the 
ore.  Gypsum  is  found  with  ore  at  Sulphur  Bank.  Magnesite  occurs  in  the 
New  Almaden,  and  perhaps  elsewhere,  with  calcitic  carbonates.  Barite  is 
found  with  cinnabar  in  the  Oathill,  and  this  is  the  only  case  known  of 
the  occurrence  of  barite  with  cinnabar  in  California.1  Apophyllite  in  fine 

'Au  erroneous  statement  with  reference  to  an  occurrence  of  barito  in  this  State  will  bo  oxplai 1 

further  along.     It  is  also  reported  with  cinnabar  in  Utnli. 


ASSOCIATED  MINERALS.  389 

crystals  occurs  in  the  New  Almaden,  though  at  some  distance  from  ore,  in 
a  geode,  accompanied  by  bitumen.  Specularite  is  found  in  hard  crusts  with 
pyrite  and  cinnabar  in  the  Rinconada  and  limonite  is  naturally  common 
near  croppings.  Melanterite  often  forms  in  the  drifts  of  the  mines.  Copi- 
apite  occurs  both  at  Redington  and  at  Sulphur  Bank,  as  was  proved  both 
by  quantitative  analysis  and  by  crystallographic  properties.  Among  the 
efflorescences  in  the  mines  are  epsomite  from  the  Redington  mine,  of  which 
a  quantitative  analysis  was  made,  ammonia-alum  from  Sulphur  Bank,  and 
borates  from  the  s:nne  locality.  Pyrolusite  is  found  at  the  San  Carlos  and 
the  alta  of  the  New  Almaden  contains  manganese.  Morenosite  coats  one 
specimen  of  millerite,  and  nickel  silicates  are  found  at  the  St.  John's  and  at 
the  I'lKenix,  but  no  nickel  carbonate  has  been  observed.  Stibnite  occurred 
with  cinnabar  at  the  Manhattan,  the  Manzanita,  and  at  the  Stayton  mines. 
The  red  sulphide  of  antimony,  for  which  I  have  suggested  the  name  meta- 
stibnitc,  and  arsenic  sulphides  are  abundant  in  the  deposits  of  Steamboat 
Springs.  Chromite  is  abundant  in  the  serpentine  of  the  Coast  Ranges,  and 
hence  occurs  also  near  cinnabar,  though  probably  formed  long  before  the  ore. 
In  the  New  Almaden  some  of  the  gangue  is  stained  green  with  chromium  sili- 
cates. The  green  stains  were  tested  chemically;  under  the  microscope  they 
appear  as  greenish,  cryptocrystalline  grains.  Two  new  hydrated  chromium 
sulphates  were  found  in  the  Redington  mine  at  the  point  where  solfataric 
gases  issue,  and  they  are  doubtless  the  result  of  the  action  of  these  gases  on 
chromite  in  the  serpentinoid  rocks.  It  is  proposed  to  call  the  more  highly 
hydrated  compound  redingtonite  and  that  with  loss  water  knoxvillite.  It  is 
needless  to  point  out  that  a  considerable  number  of  the  minerals  enumerated 
above  are  products  of  decomposition  processes  which  have  taken  place  since 
the  original  deposition  of  the  ore  and  gangue. 

Microscopical  character. — Many  thin  sections  of  the  ore  from  different  mines 
have  been  cut,  but  under  the  microscope  they  give  results  so  uniform  that 
the  information  thus  obtained  can  be  very  briefly  stated.  The  cinnabar  is 
transparent  only  when  the  section  is  unusually  thin.  It  is  ordinarily  only 
faintly  translucent,  transmitting  dark-red  rays,  and  is  much  better  observed 
by  reflected  than  transmitted  light.  As  a  rule  the  cinnabar  seen  in  slides 
forms  aggregates  with  only  occasional  crystalline  outlines,  which  are  usually 


390  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

traces  of  prismatic  faces.  A  few  isolated  and  well  developed  crystals  have 
been  found  showing1,  in  addition  to  the  prismatic  faces,  terminal  rhombo- 
hedrons.  Cinnabar  is  often  met  with  in  dust-like  aggregates  disseminated 
through  quartz,  and  with  high  powers  this  .dust  often  resolves  itself  into 
beautiful  arborescent  and  capillary  forms.  In  some  hand  specimens,  too, 
quartz  may  be  seen  reddened  throughout  the  mass  by  disseminated  ore. 
These  fibrous  forms  of  the  mineral  are  usually  associated  with  concretionary 
structure  and  the  ore  is  often  deposited  in  concentric  layers  parallel  to  those 
of  the  accompanying  quartz  or  at  the  centers  of  geodes.  Good  crystals  vis- 
ible with  the  naked  eye  are  very  uncommon.  Some  such  occurred  in  the 
upper  portions  of  the  New  Idria  mine  and  were  secured  for  the  collection 
by  the  courtesy  of  Mr.  J.  W.  C.  Maxwell.  These  are  tabular  and  present 
some  remarkable  characteristics,  which  will  be  discussed  in  a  separate  paper. 

Vast  quantities  of  silica  occur  with  cinnabar  at  most  of  the  California 
mines,  and  a  large  part  of  this  material  consists  of  mixtures  of  opal  and 
crystalline  silica.  Such  mixtures  have  long  been  known  in  geological  liter- 
ature as  chalcedony,  and  the  term  is  used  in  that  sense  in  this  volume. 
Professor  Rosenbusch  has  shown,  however,  that  the  fibrous  silica  crystals 
so  common  in  these  mixtures  possess  negative  double  refraction  and  are 
distinct  from  quartz.  He  calls  this  mineral  simply  chalcedony.1  It  seems 
to  mo  that  the  adoption  of  this  name  for  this  purpose  will  lead  to  much 
confusion,  since  chalcedony  has  been  freely  employed  in  literature  in  the 
other  sense.  A  very  slight  modification  of  the  term,  however,  would 
obviate  this  objection  and  would  seem  to  escape  any  fresh  ones.  Cltulci'il- 
finitu  at  once  suggests  a  mineral  characteristic  of  chalcedony,  yet  not  iden- 
tical with  it.  So  far  as  I  know  it  has  not  hitherto  been  employed  in  any- 
sense,  and  I  venture  to  propose  it  for  the  anhydrous  silica  with  negative 
double  refraction  described  by  Professor  Rosenbusch. 

In  a  great  majority  of  cases  the  minerals  immediately  accompanying 
the  cinnabar  are  quartz  and  chalcedonite,  and  no  case  has  been  observed 
in  which  the  cinnabar  particles  were  directly  embedded  in  opal,  although 
the  greater  part  of  the  area  of  some  slides  is  occupied  by  the  last-named 
mineral.  Minute  cracks  in  the  opal  are  often  filled  with  crystals  of  cinna- 

'  Mik.  Phys.,  vol.  1,  1685,  p.  345. 


MICROSCOPICAL  CHARACTER  OF  ORE.  391 

bar  and  of  silica,  and  these  indicate  that  the  deposition  of  opal  preceded 
that  of  such  cinnabar  and  the  accompanying  quartz  and  chalcedonite. 
The  mixture,  however,  is  sufficiently  intimate  to  compel  the  conclusion  that 
opal  deposition  cannot  have  been  an  independent  process,  but  only  an  early 
stage  of  the  same  process  by  which  cinnabar  was  ultimately  deposited.  It 
is  possible  that  there  ma}-  be  cases  in  which  cinnabar  is  directly  embedded 
in  opal,  though  this  association  is  not  represented  among  the  slides,  and  it  is 
certain  from  field  observations  that  very  little  of  the  cinnabar  can  occur  in 
this  way.  It  seems  more  probable  that  the  conditions  attending  the  actual 
crystallization  of  the  cinnabar  were  also  favorable  to  the  crystallization  of 
the  silica.  Calcite  and  dolomite,  especially  the  former,  are  found  in  a  large 
proportion  of  the  slides.  The  deposition  or  formation  of  more  or  less  dolo- 
mitic  carbonates  appears  from  the  slides  to  have  preceded  the  deposition  of 
opal,  quartz,  chalcedonite,  and  cinnabar  in  most  cases,  but  in  some  instances 
the  carbonates  fill  interstices  in  chalcedony,  showing  that  carbonates  were 
deposited  at  distinct  periods.  Cinnabar  is  sometimes  deposited  in  direct 
contact  with  the  carbonates,  but  occurs  in  this  way  much  more  rarely  than 
in  quartz.  Field  observations  also  show  an  irregularity  corresponding  to 
that  observed  under  the  microscope.  In  most  of  the  mines  silica  predomi- 
nates in  some  portions  and  carbonates  in  others.  This  variation  is  not  only. 
characteristic  of  the  deep  mines,  but  also  of  Steamboat  Springs,  where 
some  areas  of  the  spring  deposits  are  almost  pure  chalcedony,  while  others 
consist  largely  of  carbonates.  The  intimate  association  of  cinnabar  with 
opal  and  carbonates  is  of  course  sufficient  to  show  that  the  ore  is  deposited 
from  solutions. 

inclosing  rocks. —  The  country  rock  of  the  cinnabar  deposits  is  of  the  most 
varied  character,  and  I  am  unable  to  see  that,  excepting  from  a  mechanical 
point  of  view,  the  rock  has  exerted  any  influence  on  deposition.  The  old- 
est rock  in  which  cinnabar  occurs  is  granite,  in  which  the  main  part  of  the 
deposit  at  Steamboat  Springs  is  found.  The  ore  occurs  in  every  variety  of 
the  early  Cretaceous  rocks,  in  unaltered  sandstones,  and  also  in  phthanite, 
pseudodiabase,  pseudodiorite,  glaucophane  schists,  and  serpentine.  The 
most  important  deposits  occur  in  the  metamorphosed  rocks,  but  this  seems 
to  be  due  only  to  their  hardness,  as  will  be  explained  a  little  later.  Chico 


392  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sandstones  not  considerably  altered  contain  cinnabar  at  New  Idria.  In 
San  Luis  Obispo  County  the  ore  is  found  in  unaltered  sandstones  believed 
to  be  Miocene;  at  Sulphur  Bank  rich  ore  was  found  in  modern  lake  beds; 
the  andesite  of  Clear  Lake  contained  deposits;  so,  also,  does  the  andesite 
near  Calistoga ;  and  the  same  association  occurs  at  Mt.  Diablo;  traces  of 
cinnabar  occur  in  the  basalt  of  Steamboat,  and  a  large  part  of  the  best  ore 
of  Sulphur  Bank  was  found  in  this  recent  lava.  On  the  /Etna  property 
ore  is  also  found  in  basalt. 

Alteration  of  the  rocks. —  The  rocks  adjoining  ore  deposits  have  in  many  cases 
been  greatly  modified.  Metamorphic  rocks  often  appear  to  have  been  con- 
verted into  or  replaced  by  more  or  less  dolomitic  carbonates  by  the  action 
of  solutions.  This  is  inferable  both  from  field  and  laboratory  observations; 
for,  while  limestone  is  extremely  rare  in  the  Coast  Ranges  as  a  whole,  large 
masses  of  more  or  less  impure  carbonates  appear  in  the  mines.  This  is 
especially  noticeable  at  New  Almaden,  where  also  the  concretionary  struct- 
ure of  a  part  of  the  material  shows  the  foreign  origin  of  the  mineral.  The 
metamorphic  rocks  converted  into  carbonates  are  usually  stained  brown  by 
ferric  oxide  and  ferrous  carbonate  and  retain  the  general  habitus  of  the 
associated  metamorphic  rocks  which  have  not  undergone  this  change;  but 
it  is  often  difficult  to  determine  the  exact  character  of  the  original  material. 
The  metamorphic  rocks  where  they  are  unaffected  by  carbonate  solutions 
vary  so  capriciously  that  the  immediate  association  of  psendodiabase  with 
carbonated  rock  does  not  prove  that  the  latter  is  an  altered  form  of  the 
former.  Under  the  microscope  it  is  found,  too,  that  the  alteration  by  car- 
bonate solutions  so  quickly  obliterates  the  character  of  the  rock  modified 
that  satisfactory  transitions  are  comparatively  rare.  Both  serpentine  and 
the  granular  metamorphic  rocks  seem  to  be  subject  to  this  conversion. 

siiicification. —  In  the  third  chapter  I  have  referred  to  a  widespread  partial 
silicification  of  the  Coast  Ranges,  which  seems  to  have  formed  the  latest 
phase  of  the  Post-Neocomian  metamorphism.  In  connection  with  the  ore 
deposition  there  has  also  been  localized  silicification,  sometimes  on  a  large 
scale.  The  products  of  the  two  periods  of  silicification  are  ordinarily  very 
distinct,  though  doubtless  there  are  cases  in  the  neighborhood  of  mines  in 
which  it  might  be  impossible  to  refer  the  silica  with  certainty  to  one  or  the 


SILICIFICATIOff.  393 

other  period.  The  Post-Neocomian  silicification  altered  a  portion  of  the 
shales  to  jaspery  masses  or  phthanite  and  formed  in  these  and  other  rocks 
innumerable  minute  veins  of  quartz.  The  silicification  attendant  upon  ore 
deposition  at  a  much  later  date  resulted  m  the  formation  of  great  quantities 
of  opal,  accompanied  by  a  small  amount  of  crystalline  silica.  The  opal  is 
usually  colored,  and,  as  seen  in  hand  specimens,  is  often  deep  black,  so  that 
it  considerably  resembles  some  varieties  of  obsidian.  It  occurs  in  meta- 
morphosed rocks  sometimes  as  small  spots  and,  again,  near  ore  bodies  in 
large  quantities.  It  is  much  more  frequent  in  the  mines  to  the  north  of 
San  Francisco  than  to  the  south,  though  few  deposits  are  unaccompanied 
by  small  quantities  of  this  material.  I  am  not  aware  that  it  is  found  any- 
where far  from  known  traces  of  cinnabar  and  I  look  upon  it  as  an  indica- 
tion of  the  probable  presence  of  quicksilver  wherever  found.  Its  intimate 
relation  with  metalliferous  solutions  is  shown  by  the  fact  that  it  is  seldom 
if  ever  free  from  sulphides  of  iron  or  nickel,  which  may  sometimes  be  seen 
under  the  microscope  when  they  are  macroscopically  invisible.  The  opal  is 
seldom  absolutely  free  from  quartz  and  chalcedonite,  and  sometimes  a  small 
amount  of  carbonates  appears  in  it.  The  chalcedonite  and  quartz  microlites 
in  the  opal  are  not  infrequently  radially  arranged,  forming-  globules  which 
dot  the  entire  field.  Sometimes  a  perfect  net  of  minute  bands  of  quartz 
traverses  the  opal.  This  net  has,  however,  nothing  to  do  with  serpentine, 
for,  while  net  structure  does  not  occur  among  the  serpentines  of  the  quick- 
silver belt,  it  is  manifest  under  the  microscope  that  this  quartz  net  repre- 
sents an  infiltration  into  fissured  opal.  The  opal  usually  carries  a  few  fluid 
inclusions  and  microlites  of  an  indeterminable  character. 

Some  of  the  opal  or  opaline  chalcedony  has  certainly  been  deposited  in 
pre-existing  openings,  but  a  large  part  of  it  must  have  been  deposited  by  sub- 
stitution for  rocks.  This  conclusion  was  drawn  from  observation  in  the  mines, 
where  the  shape  of  the  opaline  masses  and  the  manner  in  which  it  was  min- 
gled with  country  rock,  particular!}'  serpentine,  forbade  the  supposition  that 
it  had  filled  cavities  or  fissures.  Many  slides  present  no  evidence  of  pseudo- 
morphism, being  entirely  occupied  by  opal,  with  trifling  admixtures  of 
quartz  etc.  Others,  however,  show  clear  transitions  to  serpentine  and,  in 
particular,  distinct  remnants  of  the  <rr,ate  structure  so  characteristic  of  the 


394  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

California  serpentine.  This  structure  is  also  seen  to  be  gradually  effaced 
as  the  quantity  of  opal  increases.  The  silica  solutions  seem  clearly  to  have 
permeated  more  or  less  fractured  serpentine,  extracting  the  bases  and  de 
positing  the  opal,  the  course  of  decomposition  being  the  same  indicated  for 
the  silicified  serpentine  of  the  Bfihmerwald  by  Schrauf l  and  for  the  rocks 
at  Bilin  by  Doelter.2  Remnants  .of  hornblende  have  been  detected  in  one 
of  the  opals  and  are  probably  explained  on  the  supposition  that  pseudo- 
diorite  is  subject  to  replacement  by  opal.  In  one  case,  from  the  Lake  mine, 
glaucophane  rocks  have  also  undergone  a  similar  change,  glaucophane  and 
distinct  traces  of  the  structure  of  the  schist  in  which  that  mineral  occurs 
remaining  in  a  portion  of  the  slide,  but  gradually  passing  over  into  micro- 
crystalline  quartz.  There  is  similar  evidence  that  chloride  sandstones  have 
been  impregnated  with  opal,  and  one  such  specimen  from  Knoxville  con- 
tains perowskite.  It  forms  small  cubes  of  a  violet-brown  color,  which 
refract  light  strongly.  Twins  formed  by  two  cubes  united  according  to  the 
spinel  law  and  one  form  similar  to  the  pentagonal  dodecahedron  were  also 
observed.  It  has  been  found  in  the  Coast  Ranges  only  in  this  one  specimen, 
where  it  formed  at  the  same  time  as  the  opal. 

HYPOTHESIS    OF    SUBSTITUTION. 

Substitution  of  ore  for  rock  doubtful. AllTlOSt  fl'OIll  tllO  beginning  of  the  illVCSti^a- 

o  o  o 

tions  described  in  this  volume  my  attention  has  been  directed  to  cases  of 
replacement,  including  those  by  cinnabar;  but  I  have  entirely  failed  to  find 
any  valid  evidence  that  this  process  has  gone  on  to  any  considerable  extent. 
On  the  contrary,  careful  study  of  much  ore  in  place  and  under  the  microscope 
seems  to  show  that  the  cinnabar  and  the  gangue  minerals  immediately  accom- 
panying it  have  been  deposited  exclusively  in  pre-existing  openings.  These 
are  usually  fissures  in  the  rocks,  and  most  large  bodies  of  ore  seem  to  me  to 
consist  of  crushed  rock  the  interstices  of  which  have  been  filled  with  cinna- 
bar, quartz,  and  carbonates.  I  have  never  met  with  an  instance  in  which  the 
ore  masses  were  bounded  by  rock  the  surface  of  which  presented  the  peculiar 
pits  and  corrugations  so  characteristic  of  corrosion.  Where  compact  rock  is 

1  Tschennak's  Miuernl.  Mittlidl.,  1873,  p.  13. 
2Zeitsch.  fur  Krys.  unil  Min.,  Groth,  vol.  C,  1881,  p.  321. 


SUBSTITUTION. 


[WITIBSITTU 


in  contact  with  cinnabar  the  ore  does  not  penetrate  it,  ff^*aemasg?nsts  ;  and 
the  contact  surface  preserves  the  same  geometrical  character  as  freshly  fract- 
ured rock  of  the  same  kind  presents.  Had  an  active  process  of  replacement 
gone  on,  one  would  expect  to  find  angularmasses  of  ore  containing  rounded 
kernels  of  rock,  just  as  in  the  partially  serpentinized  rocks  globular  masses 
of  sandstone  or  pseudodiabase  are  found  coated  by  less  regular  layers  of  ser- 
pentine. I  have  never  met  with  cinnabar  bearing  this  relation  to  serpentine 
or  to  other  rocks.  When  the  rocks  are  porous,  or  practically  when  they 
consist  of  sandstone  of  loose  texture,  the  ore  does,  indeed,  permeate  them  and 
the  interstitial  space  is  filled  up  with  cinnabar  and  quartz  ;  but  neither  in  such 
specimens  nor  in  the  slides  does  any  evidence  present  itself  that  replacement 
has  occurred.  So  far  as  I  know,  the  case  most  nearly  simulating  replace- 
ment is  the  deposit  at  Steamboat,  where  the  cinnabar  is  chiefly  found  dis- 
seminated in  decomposed  granite.  But  here  much  of  the  granite  is  reduced 
to  a  loose,  gravelly  mass,  in  which  there  is  no  ore,  and  this  material  in  every 
respect  resembles  that  in  which  the  ore  is  found.  I  can  form  no  other  con- 
clusion J.han  that  the  decomposition  and  impregnation  with  cinnabar  were 
independent  phenomena.  The  precipitation  of  cinnabar  took  place  in  the 
granite  only  after  space  was  made  to  receive  it,  and  the  deposition  of  the  ore 
was  not  a  condition  of  the  solution  of  the  granite  mass.  So,  also,  in  the 
basalt  of  Sulphur  Bank  cinnabar  is  found  partially  filling  crevices,  which 
have  manifestly  first  been  enlarged  from  mere  fissures  by  sulphuric  acid  or 
by  other  means  independent  of  the  precipitation  of  cinnabar.  Were  the  ore 
deposited  by  replacement,  there  would  also  be  a  closer  relation  than  seems 
to  exist  between  the  chemical  character  of  the  rock  and  the  richness  of  the 
deposits.  In  the  metamorphic  series  phthanites,  pseudodiabase,  serpentine, 
and  altered  sandstone  seem  indifferently  to  limit  rich  ores,  and  such  ores 
are  also  found  in  contact  with  basalt.  The  amount  of  disturbance  (except 
in  the  case  of  porous  sandstones),  and  not  the  quality  of  the  rock,  is  approxi- 
mately proportional  to  the  amount  of  ore. 

The  absence    of   ore  in   the  opal    mysterious. 1    Cannot   Satisfactorily   aCCOUllt  fol*   tllO 

fact  that,  while  various  rocks  adjoining  ore  bodies  become  silicified,  the 
cinnabar  is  either  absolutely  or  substantially  confined  to  fissures,  in  which 
it  is  usually  associated  with  quartz.  If  the  solutions  which  opalized  the 


396  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

serpentine  contained  mercuric  sulphide,  it  seems  strange  that  it  should  not 
have  crystallized  out  in  the  silicified  mass  from  mere  relief  from  pressure 
and  diminution  of  temperature.  Either,  then,  the  silicification  was  effected 
before  the  solutions  became  charged  with  mercuric  sulphide  or  the  cinnabar 
was  precipitated  in  the  crevices  before  the  solutions  made  their  way  into 
the  rock.  It  seems  fairly  certain  that  a  large  part  of  the  opalization  took 
place  before  the  main  deposition  of  the  ore ;  but,  as  the  solutions  at  the 
actual  time  of  ore  deposition  were  certainly  siliceous,  a  portion  of  the 
opalization  was  doubtless  contemporaneous  with  the  precipitation  of  cin- 
nabar, and,  although  the  earlier  solutions  may  have  been  poor  in  mercury 
compared  with  the  later  ones,  it  does  not  seem  to  me  probable  that  they 
were  entirely  barren  at  any  time.  I  can  only  conglude  that  the  cinnabar 
was  separated  from  the  solutions  remaining  in  the  fissures  when  the  siliceous 
fluid  permeated  the  rocks.  Some  mechanical  process,  more  or  less  anal- 
ogous to  dialysis,  seems  to  be  the  only  natural  explanation  of  such  a  sepa- 
ration. There  are  a  number  of  phenomena  in  mineral  chemistry  which 
seem  to  require  some  such  hypothesis  as  this  for  their  adequate  explanation; 
but  I  am  not  prepared  to  offer  any  positive  evidence  in  favor  of  it  and 
it  is  suggested  only  as  a  logical  possibility. 

pseudomorphism  and  substitution. — The  hypothesis  that  any  ore  has  been  de- 
posited by  substitution  for  country  rock  is  equivalent  to  the  hypothesis 
that  the  ore  has  replaced  the  mineral  constituents  of  the  rock  molecule  for 
molecule.  The  ore  minerals  must  therefore  be  capable  of  forming  pseudo- 
morphs  after  such  of  the  component  minerals  of  the  rock  as  are  crystalline, 
and  of  replacing,  without  essential  change  of  form,  dense  masses  of  these 
minerals  or  of  components  which  are  not  crystalline.  When  it  is  known 
that  any  mineral,  whether  an  ore  or  not,  forms  pseudomorphs  after  other 
substances,  it  is  not  unreasonable  to  assert  that  it  may  replace  rock  masses 
consisting  of  these  substances.  Thus  talc  is  known  to  occur  pseudomor- 
phically  after  a  great  number  of  minerals,  and  to  assert  that  it  may  replace 
whole  masses  of  rocks,  composed,  for  example,  of  pyroxene,  dolomite,  and 
quartz,  is  only  to  maintain  that  the  physical  conditions  under  which  it  may 
form  pseudomorphs  after  all  three  of  these  minerals  are  the  same.  But 
when  it  is  asserted  that  an  ore  replaces  rocks  composed  of  minerals  after 


SUBSTITUTION.  397 

which  the  ore  is  not  known  to  form  pseudomorphs  the  hypothesis  of  substi- 
tution must  be  very  carefully  weighed. 

•/  tj  o 

Cinnabar  is  reported  to  occur  as  pseudomorphs  after  several  metallic 
sulphides.  At  least  one  of  these  changes,  the  replacement  of  pyrite,  appears 
to  require  confirmation,  but  they  are  of  no  importance  here,  since  they  have 
no  bearing  on  the  theory  of  the  substitution  of  cinnabar  for  wall  rock. 
Cinnabar  is  also  known  as  a  fossilizing  mineral,  indicating  that  it  may 
replace  organic  matter.  As  has  been  stated  in  the  description  of  Sulphur 
Bank,  cinnabar  is  precipitated  from  solution  by  ammonia,  though  not  at 
high  temperatures  and  pressures.  It  is  possible  that  herein  lies  the  expla- 
nation of  the  fact  that,  while  cinnabar  is  known  to  have  replaced  organisms, 
the  presence  of  carbonaceous  shale  or  of  bituminous  substances  in  the 
mines,  whether  of  California  or  Europe,  is  not  commonly  of  itself  any  indi- 
cation of  unusually  rich  or  abundant  ore.  It  may  be,  however,  that  such 
substances  sometimes  have  an  appreciable  effect.  "If  quicksilver,"  says 
de  Prado,  "exhibits  an  affinity  or,  if  you  choose,  a  propensity  for  any  other 
substance,  it  is  for  carbonaceous  or  bituminous  matter."1 

Cinnabar  is  also  said  to  form  pseudomorphs  after  two  non-metallic 
minerals,  dolomite  and  barite.  Dr.  E.  F.  Durand  is  the  only  authority  cited 
for  the  statement  that  it  replaces  barite.2  On  reference  to  his  paper  it 
appears  that  this  observer  found  in  the  Redington  mine  a  tabular  crystal 
of  cinnabar  which  did  not  seem  to  him  referable  to  the  rhombohedral  sys- 
tem ;  and  he  hence  inferred  that  it  must  be  an  example  of  dimorphous  cin- 
nabar or  a  pseudomorph  of  cinnabar  after  some  other  mineral,  very  likely 
barite.  This  is  a  mere  suggestion,  and  not  an  assertion.  It  was  unsup- 
ported by  measurements  of  angles  or  other  evidence,  and  barite  has  never 
been  found  in  the  Redington  mine.  It  is  clearly  incorrect  to  cite  this  crys- 
tal as  a  case  of  the  otherwise  unknown  pseudomorphism  of  cinnabar  after 
barite. 

Of  the  pseudomorphism  of  cinnabar  after  dolomite  also  only  one  case 
seems  to  be  recorded.  It  is  said  to  have  been  reported  by  Blum3  in  1863 

1  Bull.  Soc.  g«Sologique  France,  2d  series,  vol.  12,  1855,  p.  24. 
2 Proc.  Cal.  Acad.  Nat,  Sci.,  vol.  4, 1872,  p. 211. 

3  Pseuilomorphoseii,  Appendix  III,  cited  in  Allg.  und  chem.  Geol.,  Roth.,  vol.  1,  1879,  p.  184.     This 
appendix  is  not  at  present  accessible  to  me. 


398  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

on  the  authority  of  Krantz  as  occurring  in  the  Idria  mine.  Since  that  time 
Lipold  has  written  two  careful  memoirs  on  the  Idria  deposit,  but  lie  does  not 
refer  to  these  pseudomorphs.  On  the  contrary,  he  states  that  in  the  dolomite 
rock  cinnabar  occurs  for  the  most  part  as  mere  paints  or  thin  incrustations 
(zarte  Anfliige),  and  mentions  dolomite  crystals  and  cinnabar  as  of  simulta- 
neous deposition  from  the  ore-bearing  solutions.  In  view  of  these  facts  and 
considering  that  dolomite  and  cinnabar  each  show  a  considerable  variety  of 
faces  of  the  rhombohedral  system,  to  which  both  belong,  it  appears  to  me 
nearly  certain  that  Krantz  was  in  error  and  that  cinnabar  has  not  been 
observed  replacing  dolomite 

The  substitution  of  a  metallic  sulphide  for  a  sulphate  or  a  carbonate 
of  an  alkaline  earth  seems  strange,  but  there  is  no  reason  to  doubt  that  such 
transformations  occur.  While  it  is  extremely  doubtful  whether  cinnabar 
has  ever  been  found  as  pseudomorphs  after  non-metallic,  inorganic  minerals, 
there  is  good  evidence  that  galena  has  replaced  calcite,  and  probably  also 
dolomite.  Sillern  found  pseudomorphs  after  calcite  at  Andreasberg  and  at 
Pfibram1  and  A.  E.  Reuss  found  at  Rodnau,  in  Transylvania,  transforma- 
tions of  calcite  into  a  mixture  of  galena  and  pyrite.2  Such  replacements  have 
also  attracted  attention  in  this  country.  In  1880  I  suggested  that  there  was 
evidence  tending  to  prove  that  the  lead  ores  of  Eureka,  which  are  galena 
and  its  derivatives,  had  replaced  the  more  or  less  dolomitic  limestone  in  which 
the  deposits  are  inclosed.3  Later  Mr.  J.  S.  Curtis  made  more  observations 
on  the  same  deposits,  which  seemed  conclusive  of  this  substitution,4  and  Mr. 
S.  F.  Emmons  has  shown  that  the  same  conclusion  is  to  be  drawn  with 
reference  to  the  lead  deposits  in  limestone  at  Leadville.5  In  case  of  a  real 
replacement  the  rock  replaced  will  be  represented  in  the  resulting  ore  bodies 
only  by  residual  kernels,  and  where  action  has  been  vigorous  few  such 
kernels  will  remain.  Both  Mr.  Curtis  and  Mr.  Emmons  call  attention  to 
the  rarity  of  calcium  carbonate  in  the  lead  ores  of  the  respective  districts 

'Neues  Jahrtmch  fur  Mineral.,  1651,  p.  397.  Silleui's  observations  \vcro  not  called  iu  question  by 
Reuss,  as  seems  to  have  been  supposed  (Allg.  .Geol.,  Rotli,  vol.  1,  p.  17'J),  for,  though  tins  hitter  did 
not  observe  tbis  change  at  Pfibram,  iu  speaking  of  the  Rodnau  occurrence  he  mentions  the  replace- 
ment as  "already  proved  elsewhere,"  and  ho  can  have  referred  only  to  Sillem's  observations. 

1  Sitzungsber.  k.  Akad.  Wiss.,  Wien,  vol.  10,  1853,  p.  67. 

3  First  Ann.  Rept.  U.  S.  Geol.  Survey,  1880,  p.  38. 

4Silver-Lead  Deposits  of  Eureka,  Nevada,  MOD.  U.  S.  Geol.  Survey  No.  7,  ISM,  p.  104. 

6Geology  and  Mining  Industry  of  Leadvillo,  Colorado,  Mou.  U.  S.  Geol.  Survey  No.  12,  1886, 
passim. 


SUBSTITUTION.  399 

which  they  investigated.     Had  they  been  deceived  as  to  the  process  of 
deposition  and  were  the  ores  in  reality  deposited  in  interstitial  spaces  in 
the  limestone  or  from  solutions  carrying  large  quantities  of  carbonates  of 
.  calcium  and  magnesium,  these  would  have"  been  abundant  in  the  ore. 

Alleged  cases  of  substitution. — The  theory  that  cinnabar  has  been  deposited  by 
substitution  for  rock  has  often  been  maintained.  So  far  as  I  know  it  was 
first  suggested  by  de  Pi-ado,  who  believed  that  in  the  Almaden  mine  cinna- 
bar had  replaced  a  portion  of  the  quartzite  All  the  geological  observers 
who  have  written  on  this  deposit  since  de  Prado  have  reached  or  adopted 
the  same  opinion,  but  the  only  proof  given  is  that  some  of  the  impregna- 
tions are  so  rich  us  to  preclude  the  supposition  that  cinnabar  occupies  only 
interstitial  space.  This  is  a  statement  which  can  be  to  some  extent  tested 
by  computation.  Quartz  sand,  well  shaken  down,  weighs  120  pounds  per 
cubic  foot,  while  solid  quartz  weighs  165  pounds  per  cubic  foot.  The 
packed  sand  therefore  contains  273  per  cent,  of  interstitial  space.  Were 
this  filled  with  cinnabar  of  a  specific  gravity  of  9,  the  mass  would  contain 
almost  exactly  56  per  cent,  by  weight  of  cinnabar,  or  over  48  per  cent,  of 
quicksilver.  No  very  definite  idea  is  presented  by  "well  shaken  sand," 
but  it  at  least  represents  an  accepted  experimental  result  comparable  with 
the  conditions  to  be  expected  in  natural  sand  beds.  Were  the  sand  com- 
posed of  spherical  grains  all  of  the  same  size  and  as  closely  packed  as 
possible,  so  that  every  sphere  was  in  contact  with  twelve  others,  the  mass 
would  contain  26  per  cent,  of  interstitial  space,1  and  were  this  filled  with 
cinnabar  the  mass  would  contain  nearly  47  per  cent,  of  quicksilver.  The 
richest  impregnation  which  I  was  able  to  find  in  the  Almaden  mine  or  at 
the  furnaces  contained  only  33  per  cent,  of  metal  and  the  average  yield 
of  the  mine  for  the  past  twelve  years  has  been  only  9  per  cent  If  one 
allows  1  per  cent,  for  loss  or  assumes  that  the  ore  really  contained  10  per 
cent.,  the  volume  occupied  by  the  cinnabar  was  only  3.7  per  cent.,  which 
is  less  than  half  of  the  interstitial  space  in  some  indurated  sandstones  em- 
ployed for  paving  streets.  The  richness  of  the  impregnations  is  thus  cer- 
tainly not  such  as  to  prove  that  replacement  of  quartz  by  cinnabar  has 

It 

1  Accurately,  as  I  compute  it,  1  —        ,—  =  25. 95  per  cent. 


400  QUICKSILVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

taken  place.  Microscopical  -examinations  of  the  ore  are  much  more  con- 
clusive. I  have  twenty  thin  sections  of  the  ores,  and  these  show  that,  ex- 
cepting in  the  rare  cases  in  which  the  cinnabar  is  deposited  with  barite, 
the  sulphide  has  crystallized  simultaneously  with  quartz  even  in  the  inter- 
stices of  the  sandstones,  themselves  almost  exclusively  composed  of  quartz 
Microscopically,  too,  it  may  be  seen  throughout  this  mine  that  veinlets  of 
ore  constantly  contain  quartz  as  a  gangue  mineral.  This  would  be  im- 
possible were  the  cinnabar  deposited  by  substitution  for  quartz,  for,  evi- 
dently, if  solution  of  quartz  be  a  condition  of  the  precipitation  of  cinna- 
bar, the  simultaneous  precipitation  of  the  two  minerals  cannot  occur.  The 
two  processes  are  mutually  exclusive. 

Lipold  speaks  of  the  replacement  of  constituents  of  the  Lagerschiefer  of 
Idria  by  cinnabar,  but  he  attributes  to  this  reaction  only  a  subordinate  part 
in  the  formation  of  the  deposit  and  does  not  enlarge  upon  the  theory.  These 
slates  are  carbonaceous  and  may  possibly  have  had  some  effect  upon  precipi- 
tation, but  I  saw  no  definite  evidence  of  it  and  Lipold  mentions  none. 

Professor  von  Groddeck,  in  his  interesting  memoir  on  the  new  Avala 
mine  in  Servia,1  describes  the  deposits  as  consisting  of  vein-like  zones  of  meta- 
morphosed rocks  impregnated  with  quicksilver  ore.  The  wall  rock  which 
has  been  metamorphosed  or  altered  is  chiefly  serpentine,  and  the  process  is 
one  of  silicification  accompanied  by  the  formation. or  deposition  of  carbo- 
nates. Most  of  the  cinnabar  occurs  in  stringers  or  impregnations  which  seem 
later  than  the  silicification,  but  the  silicified  serpentine  also  contains  cinna- 
bar, deposited,  in  von  Groddeck's  opinion,  at  the  time  of  the  alteration  of  the 
serpentine.  Though  he  speaks  of  the  vein  matter  as  pseudomorphic  after 
serpentine  and  as  consisting  in  part  of  cinnabar,  he  does  not  state  explicitly 
that  he  regards  the  cinnabar  as  pseudomorphic  after  serpentine.  It  is  evi- 
dently conceivable  that  while  silicification  of  the  serpentine  was  in  progress 
cinnabar  should  have  been  deposited  by  relief  of  pressure  and  temperature, 
as  was  suggested  in  a  preceding  paragraph.  Other  explanations  also  seem 
possible,  and  I  can  see  in  this  occurrence  no  sufficient  proof  that  cinnabar 
has  been  substituted  for  serpentine  molecule  for  molecule. 

Professor  von  Groddeck  also  describes  a  specimen  from  New  Almaden. 
He  regards  the  ore  as  having  replaced  serpentine,  because  it  shows  the  net 

'See  Zeitschr. fur  Berg-,  Hiitten-  and  Salinrmvrsrn.  vol.  :i3,  1885, p.  188. 


SIMILARITY  OF  THE  DEPOSITS.  401 

structure  so  common  in  serpentine  and  from  analogy  with  the  Servian  ores. 
The  net  structure  in  the  California  ores,  however,  is  rather  an  evidence  that 
it  did  not  replace  serpentine,  because  neither  at  New  Almaden  nor  elsewhere 
in  the  Coast  Ranges  has  the  net  structure  been  found  in  the  serpentine.1 

SIMILARITY    OF   THE    DEPOSITS. 

AH  the  deposits  similarly  formed. —  Everything  seems  to  point  to  the  hypothesis 
that  all  the  quicksilver  ores  of  the  Pacific  slope  have  been  formed  in  a 
similar  manner.  The  gangue  minerals  and  their  association  are  not  identi- 
cal at  all  the  mines,  but  it  will  be  found  that  the  peculiarities  offset  one 
another.  It  is  quite  true  that  quicksilver  ores  the  world  over  are  strikingly 
similar  in  composition.  The  same  minerals  which  are  found  abundantly 
with  cinnabar  in  California  are  those  most  usually  associated  with  it  else- 
where. Though  other  minerals,  such  as  sulphides  of  lead  and  copper,  are 
also  found  with  cinnabar  both  on  the  Pacific  slope  and  in  European  mines, 
they  are  rare.  These  facts  do  not  weaken  the  evidence  given  by  this 
characteristic  association  of  minerals  that  the  deposits  of-  the  Pacific  slope 
have  all  been  formed  in  the  same  manner,  but  rather  tend  to  show  that 
conditions  accompanying  the  genesis  of  European  deposits  were  similar  to 
those  which  attended  the  formation  of  the  quicksilver  ores  of  America. 

Comparison  of  the  various  localities  described  in  former  chapters 
shows  that  a  substantially  complete  series  of  transitions  exists  from  de- 
posits now  forming  to  those  in  which  there  is  every  reason  to  suppose  ore 
formation  ceased  long  since.  This  is  true  bo^h  as  to  the  method  of  genesis 
indicated  and  as  to  the  form  of  the  deposits;  but  it  will  be  convenient  to 
deal  first  with  the  former  and  then  with  the  latter  of  these  topics. 

Evidence  as  to  method  of  genesis. — There  can,  of  course,  \)G  no  possible  doubt 
as  to  the  manner  in  which  the  cinnabar  deposits  of  Steamboat  Springs  and 

1  In  my  opinion  much  caution  is  necessary  in  using  inferences  from  net  structure.  The  system  of 
fissures  so  well  known  to  lithologists  as  forming  in  olivine  does  not  appear  to  be  characteristic  of  that 
mineral  only,  but  of  most  substances  which  possess  no  distinct  cleavage.  In  (he  rocks  in  which  par- 
tially decomposed  olivine  is  found,  it  is  often  the  only  substance  without  a  pronounced  cleavage,  and 
under  these  circumstances  such  structure  may  of  course  be  appealed  to  with  coufideuce;  but,  when 
material  is  examined  which  has  undergone  at  least  two  successive  processes  of  radical  alteration,  it  does 
not  seem  to  me  any  longer  safe  to  judge  from  this  structure  alone.  Indeed,  I  have  met  with  many  very 
perfect  examples  of  net  structure  in  which  it  is  certain  that  substances  exhibiting  it  are  not  derived 
immediately  or  remotely  from  olivine. 
MON  XIIT 20 


402  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Sulphur  Bank  have  been  produced.  Both  of  these  localities  present  at  the 
surface  very  marked  peculiarities,  which  might  be  thought  to  divide  them 
sharply  from  the  deep  mines,  such  as  New  Almaden,  and  to  permit  of  no 
inference  from  one  to  the  other  as  to  the  genesis  of  ore,  though,  excepting 
for  the  occurrence  of  native  sulphur  at  the  active  springs,  the  difference 
is  physical  rather  than  mineralogical.  At  Steamboat  no  considerable  effort 
has  been  made  to  follow  the  deposit,  none  of  the  excavations,  so  far  as 
I  could  learn,  being  over  fifty  feet  deep.  At  Sulphur  Bank,  which  is  so 
closely  similar  to  Steamboat  Springs,  one  chimney  of  ore  has  been  followed 
down  for  several  hundred  feet,  and  the  ore  found  in  the  lower  workings  is 
entirely  indistinguishable  in  any  way  from  that  in  the  cold,  deep  mines  to 
the  south.  It  is  the  same  association  of  cinnabar,  quartz,  iron  sulphides, 
and  carbonates.  It  contains  no  free  sulphur;  it  permeates  very  porous 
sandstone,  but  only  fills  the  crevices  of  dense  sandstones  and  shales,  j  ust  as 
is  the  case  at  New  Idria. 

The  Manzanita  mine,  in  Colusa  County,  carries  gold  as  well  as  cinna- 
bar. The  ores  of  Sulphur  Bank  and  of  Steamboat,  as  well  as  those  of  the 
Baker  and  Redington  mines,  are  also  auriferous.  The  Manzanita,  further, 
contains  a  little  stibnite  (as  did  the  Lake  mine  at  Knoxville),  pyrite,  quartz, 
calcite,  and  considerable  quantities  of  bitumen.  The  ore  is  irregularly  de- 
posited in  the  crevices  of  the  rock.  Close  by  issue  strong,  hot  sulphur  springs, 
and  the  surrounding  country  shows  that  similar  waters  have  not  long  since 
issued  from  many  other  points  now  dry.  Though  this  deposit  lias  been  some- 
what eroded,  large  quantities  of  free  sulphur  still  remain  in  portions  of  it.  It 
thus  exhibits  the  closest  analogy  to  Sulphur  Bank,  though  active  springs 
no  longer  issue  from  it.  It  differs  from  Sulphur  Bank,  however,  in  the  fact 
that  no  eruptive  rock  exists  in  the  immediate  neighborhood,  nor,  so  far  as  is 
known,  for  a  distance  of  several  miles.  This  is  an  important  peculiarity. 
Other  small  quicksilver  mines  occur  within  short  distances  of  the  Man- 
zanita. 

The  neighborhood  of  ./Etna  Springs,  in  Napa  County,  is  very  instruct- 
ive. Here  within  a  circle  of  three  miles  in  diameter  lie  numerous  deposits 
belonging  to  the  Napa  Consolidated  and  the  ^Etna  Companies.  From  one 
of  these,  the  Valley  mine,  now  abandoned,  flow  the  hot  sulphur  springs 


SIMILARITY  OF  THE  DEPOSITS.  403 

used  as  medicinal  baths.  Cinnabar  was  obtained  from  the  opening  from 
which  the  spring-  flows.  The  other  claims  do  not  show  especially  elevated 
temperatures  At  the  Starr  claim  cinnabar  occurs  at  the  contact  between 
a  dike  of  basalt  and  the  sandstone  wall,  the  metal  being  found  both  in  the 
decomposed  lava  and  in  the  sedimentary  rock.  This  mine  has  produced 
5,000  flasks  of  quicksilver  and  is  not  exhausted.  A  second  very  similar 
claim  is  the  Silver  Bow,  in  which  the  greater  part  of  the  cinnabar  is  derived 
from  the  decomposed  basalt  near  the  sandstone  wall.  There  is  no  reason 
to  suppose  that  the  eight  productive  deposits  of  this  small  area  have  been 
produced  by  different  methods  or  at  essentially  different  periods,  and  the 
association  of  those  mentioned  above  with  hot  sulphur  springs  and  basalt  is 
sufficient  evidence  that  the  genesis  of  the  deposits  was  substantially  the  same 
as  at  Sulphur  Bank.  The  minerals  associated  with  cinnabar  in  the  district 
and  the  general  characteristics  of  the  ore  are  exactly  the  same  as  in  the  mines 
to  the  south  of  San  Francisco. 

Hot  springs  and  cinnabar  are  also  closely  associated  near  Calistoga,  and 
the  hot  sulphur  springs,  miscalled  geysers,  in  Sonoma  County,  lie  within  a 
short  distance  of  a  number  of  small  quicksilver  mines.  At  Knoxville  many 
strong  mineral  springs  are  still  depositing  calcareous  sinter,  which  in  some 
cases  contains  borax,  but  the  water  is  no  longer  hot.  In  the  Redington 
mine  hot  sulphurous  gases  are  evolved  at  certain  points  and  small  amounts 
of  crystallized  sulphur  are  being  deposited.  It  is  barely  possible  that  in  this 
case  some  secondary  action  raises  the  temperature  and  induces  the  evolution 
of  sulphurous  and  sulphydric  acids,  but  I  was  unable  to  detect  any  sufficient 
cause  for  such  action  or  any  evidence  that  it  was  secondary.  The  pyrite 
of  this  mine  does  not  decompose  readily,  and  the  phenomena  are  confined 
to  a  single  portion  of  the  mine,  as  they  could  scarcely  be  were  this  a  case  of 
decomposition.  Were  the  heat  due  to  the  oxidation  of  pyrite,  the  sulphydric 
acid  to  the  reduction  of  sulphates  by  timber,  and  the  sulphurous  acid  to  the 
decomposition  of  sulphites  or  hyposulphites,  one  would  expect  to  find  the 
phenomena  repeated  at  Other  large  mines,  such  as  New  Almaden  and  New 
Idria;  but  they  do  not  occur  in  those  mines.  The  probabilities  are  thus  all 
in  favor  of  the  supposition  that  this  is  a  veritable  trace  of  a  nearly  extinct 
solfatara.  On  the  Manhattan  claim  near  Knoxville  a  tunnel  was  run  into 


404  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

the  hill  under  the  basalt.  At  the  time  of  my  visit  it  was  inaccessible,  but 
I  was  assured  by  the  watchman,  an  old  miner,  that  a  dike  of  the  lava  was 
encountered  and  that  at  its  contact  with  the  inclosing  rock  cinnabar  oc- 
curred. Basalt  does  not  elsewhere  in  this  district  come  in  contact  with 
ore,  but  the  Redington,  Lake,  Manhattan,  and  Reed  mines  and  a  number  of 
prospects  showing  cinnabar,  as  well  as  the  mineral  springs,  are  grouped 
around  the  edges  of  the  basalt  area.  Considering  the  occurrences  near 
Knoxville  in  the  light  of  the  facts  developed  near  the  yEtna  Springs  and  at 
Sulphur  Bank,  there  appears  to  me  to  be  no  doubt  whatever  that  all  three 
localities  have  been  charged  with  cinnabar  in  the  same  manner. 

No  two  mines  on  the  quicksilver  belt  possess  a  stronger  similarity  than 
the  New  Idria  and  the  Redington.  Each  is  close  to  the  contact  between  a 
very  large  metamorphic  area  and  unaltered  rocks  ;  each  carried  large  quan- 
tities of  metacinnabarite  ;  each  was  very  irregular  in  structure  on  the  upper 
levels  and  developed  well  defined  fissures  below,  and  there  is  no  difference 
in  the  association  of  minerals  in  the  two  mines.  At  New  Idria,  however, 
there  are  no  direct  means  of  determining  the  method  of  genesis.  No  sul- 
phurous gases  or  hot  water  now  enter  the  mines,  and  the  nearest  known 
basaltic  area  is  10  miles  away.  At  the  Manzanita  also  no  eruptive  rocks 
are  found,  though  there  is  abundant  evidence  of  the  action  of  hot  springs. 
There  is  nothing  whatever  to  justify  the  supposition  that  the  deposits  of 
New  Idria  are  due  to  different  causes  than  those  which  led  to  the  formation 
of  ores  at  Knoxville  and  other  localities  north  of  San  Francisco. 

The  New  Alrnaden,  Enriquita,  and  Guadalupe  mines  lie  nearly  in  a 
straight  line,  along  which  quicksilver  has  been  found  at  numerous  points. 
No  hot  gases  or  water  are  found  in  the  mines,  but  nearly  parallel  with  them 
and  at  an  average  distance  of  about  a  mile  is  a  rhyolite  dike,  which  has 
been  followed  for  several  miles.  This  association  of  course  suggests  that 
heated  waters  of  the  volcanic  type  must  at  some  time  have  reached  the  sur- 
face in  the  neighborhood,  and  probably  along  the  line  of  the  deposits. 

The  relations  described  in  the  foregoing  paragraphs  appear  sufficient  to 
establish  the  facts  that  no  grounds  exist  for  supposing  the  various  cinnabar 
deposits  to  have  been  formed  by  different  methods  and  that  a  considerable 
number  of  them  are  due  to  the  action  of  hot  sulphur  springs.  In  the  sue- 


SIMILARITY  OF  THE  DEPOSITS.  405 

ceeding  chapters  other  grounds  will  be  stated  for  attributing  all  of  them  to 
this  cause. 

Partial  absence  of  sinters. Even    if    tll6  01'CS   of    tllG   RedlDgtOH,    Ne.W   AlllUlden, 

and  New  Iilria  mines  were  not  deposited  from  hot  springs,  like  those  of  Sul- 
phur Bank,  the  structure,  as  will  be  seen  below,  would  lead  to  the  conclusion 
that  their  present  cropping*  were  not  far  distant  from  the  surface  of  the  coun- 
try at  the  time  of  their  formation.  No  spring  deposits,  however,  were  found 
at  the  croppings,  and  the  dissemination  of  cinnabar  in  the  superficial  soil  at 
the  first  two  localities  shows  that  a  certain  amount  of  erosion  has  taken  place. 
In  this  connection  it  is  worth  observing  that  the  springs  of  Sulphur  Bank 
have  made  practically  no  accumulation  of  material  at  the  surface.  They 
have  indeed  deposited  sulphur,  but  they  have  also  extracted  a  large  amount 
of  material  from  the  basalt.  Perhaps  this  is  due  to  the  sulphuric  acid  formed 
by  oxidation  of  the  hydrogen  sulphide.  This  acid  must  convert  the  car- 
bonates into  soluble  sulphates  and  precipitate  the  silica  as  particles  which 
are  carried  off  in  suspension.  Were  the  water  to  cease  flowing  and  erosion 
to  supervene,  the  disintegrated  basalt  and  the  sulphur  overlying  the  cinna- 
bar would  quickly  be  swept  away  and  no  trace  of  surface  action  would  be 
left.  At  Steamboat  Springs,  also,  it  is  remarkable  that,  where  the  cinnabar 
is  known  to  be  tolerably  abundant,  there  is  no  superficial  layer  of  sinter. 
On  the  contrary,  a  basin  has  formed,  seemingly  by  the  collapse  of  the  dis- 
integrated granite.  The  deposits  of  calcareous  and  siliceous  sinter  are  asso- 
ciated with  the  more  recent  springs,  which  carry  but  little  quicksilver  and 
do  not  form  enough  sulphuric  ncid  to  remove  the  lime.  The  lack  of  super- 
ficial sinters  and  native  sulphur  at  New  Almaden  and  other  mines  is  there- 
fore no  indication  that  they  were  not  deposited  from  hot  springs. 

Evidence  from  the  mode  of  occurrence. If     the     SCHCS     of    quicksilver     deposits    tll6 

genesis  of  which  is  discussed  in  the  foregoing  pages  be  considered  from  the 
point  of  view  of  the  form  and  structure  of  the  ore  bodies,  nothing  incon- 
sistent with  asserted  community  of  origin  will  be  found;  on  the  contrary, 
they  form  as  perfect  a  series  of  transitions  from  a  geometrical  as  from  a 
chemical  standpoint.  That  a  close  connection  exists  between  the  deposition 
of  gold  and  that  of  quicksilver  is  certain,  and  it  is  more  than  probable  that 
other  ores  sometimes  form  in  large  quantities  under  similar  conditions;  but 


406  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

no  deposits  in,  any  part  of  the  world  offer  such  opportunities  for  the  study 
of  the  real  manner  of  deposition  as  those  discussed  in  this  memoir.  They 
therefore  constitute  an  exceedingly  important  example,  and  the  question 
whether  the  quicksilver  deposits  of  the  Pacific  slope  include  true  veins  of 
cinnabar  is  consequently  one  of  great  and  general  interest. 

That  fissure  systems  must  underlie  hot  springs  such  as  those  of  Steam- 
boat and  Sulphur  Hank  is  evident,  since  otherwise  the  waters  could  not 
reach  the  surface.  Some  geologists,  however,  are  of  the  opinion  that  hot 
springs  deposit  the  minerals  which  they  carry  in  solution  only  at  their 
orifices,  and  not  in  the  fissure  systems  which  lead  to  the  surface.  So  far  as 
quicksilver  and  the  accompanying  characteristic  minerals  are  concerned, 
deposition  is  not  actually  or  substantially  limited  to  the  surface,  as  is  shown 
conclusively  by  Sulphur  Bank,  where  ore  has  deposited  abundantly  at  con- 
siderable depths  from  ascending  currents  of  water  which  are  still  intensely 
hot.  This  ore,  too,  as  was  pointed  out  above,  is  of  precisely  the  same  char- 
acter as  that  met  in  other  mines  a  thousand  or  more  feet  from  the  surface. 
The  deposit  of  the  deep  mine  at  Sulphur  Bank,  however,  is  not  a  vein, 
though  here  and  there  stringers  of  ore  were  found  which  differed  in  no  re- 
spect from  small  veins.  Indeed,  since,  as  was  shown  in  the  earlier  portion 
of  this  chapter,  the  cinnabar  is  deposited  in  pre-existing  openings,  the  form 
which  the  deposit  takes  is  determined  by  that  of  the  fissure  system.  Whether 
in  a  particular  case  a  deposit  assumes  the  form  of  a  vein,  an  irregular  body 
(stock),  or  a  reticulated  mass  (stockwork)  does  not  depend  upon  the  direc- 
tion or  the  temperature  of  the  currents  of  the  solution,  but  upon  the  char- 
acter of  the  fissure  system.  This  system,  again,  owes  its  character  to  the 
physical  properties  of  the  rock  and  the  dynamical  influences  to  which  it  has 
been  subjected. 

While  in  nearly  all  the  quicksilver  mines  of  the  Pacific  slope  the  por- 
tions of  the  deposits  at  short  distances  from' the  surface  closely  resembled 
the  lower  part  of  that  at  Sulphur  Bank,  say  from  the  first  level  downward, 
several  of  the  mines  have  exhibited  a  much  more  regular  structure  in  the 
deeper  workings  than  has  been  detected  at  Sulphur  Bank.  I  have  endeav- 
ored to  discuss  each  of  them  without  departing  from  recognized  standards 
of  description,  but  I  have  pointed  out  the  inadequacy  of  the  familiar  ter- 


VEINS.  407 

minology  to  express  the  relations  of  these  deposits  succinctly  and  clearly. 
Merely  formal  classification  is  of  little  value,  but,  since  exhaustive  descrip- 
tions of  structure  and  form  cannot  be  given  on  every  occasion,  deposits  must 
in  some  way  be  referred  to  recognized  types;  and,  unless  such  references  are 
generally  understood  in  the  same  sense,  statements  involving  them  will  nec- 
essarily fail  to  convey  the  meaning  intended.  I  am  certain  that  the  term 
vein  as  used  by  miners  and  geologists  embraces  types  of  structure  which, 
though  closely  allied,  differ  greatly  from  one  another,  and  I  have  found  that 
many  of  the  discussions  which  constantly  arise  as  to  whether  a  particular 
deposit  is  or  is  not  a  vein  and  as  to  the  limits  of  veins  owe  their  origin  to 
the  ambiguity  of  this  term.  My  opinion  as  to  the  nature  of  the  quicksilver 
deposits  of  the  Pacific  Slope  will  perhaps  be  more  readily  intelligible  if  a 
few  paragraphs  are  devoted  to  the  discussion  of  this  subject. 

NATURE  AND  NOMENCLATURE  OF  VEINS. 

Fissures  and  cavities. — Excepting  when  ores  are  deposited  in  beds,  like  coal, 
or  in  placers,  like  gold  gravels,  the  existence  of  open  subterranean  spaces 
of  greater  or  less  size  is  a  necessary  condition  for  the  formation  of  ore 
bodies  of  any  kind.  The  ore  may  be  deposited  in  openings  which  existed 
before  deposition  began  and  which  either  were  cracks  between  masses  of 
rock  broken  asunder  or  were  interstices  in  porous  rock,  like  sandstone. 
Room  for  the  ore  may  also  be  made  by  solution  of  the  rock  mass  either 
before  ore  deposition  or  during  that  process.  It  is  a  mistake,  however,  to 
suppose  that  the  masses  stoped  out  in  the  exploitation  of  mines  usually 
represent  spaces  which  were  empty  before  the  deposition  of  ore  in  them. 
Tt  is  said  that  cases  occur  in  which  open  caves  in  limestone  have  been  filled 
with  ore,  but  cavities  of  this  kind  appear  to  be  confined  to  limestone  and  to 
have  formed  only  above  the  water  level  of  the  district  by  the  solvent  action 
of  surface  waters  charged  with  carbonic  acid.  Ore  deposits,  however,  are 
by  no  means  confined  to  limestones  and  are  more  often  found  in  rocks 
of  this  class  which  have  never  been  drained  than  in  those  which  have 
been  exposed  under  the  conditions  needful  for  the  formation  of  caverns. 
It  is  also  conceivable  that  yawning  fissures  should  form  in  the  earth's  crust 
and  that  these  should  be  filled  up  solely  with  ore  and  gangue  minerals;  but 


408  QUICKSILVKU  J)KL'OSITS  OF  TUE  PACIFIC  SLOPE. 

such  cases,  if  they  exist,  are  exceptional.  All  observations  and  theory 
point  to  the  conclusion  that  most  fissures  are  formed  under  a  compressive 
stress  of  greater  or  less  violence  or  that  a  tendency  to  compress  the  rocks 
into  folds  gives  rise  to  fissures  and  faults  when  the  applied  force  exceeds  the 
tenacity  of  the  rocks.  It  is  also  well  known  that  in  faulting  the  hanging 
wall  commonly  sinks  relatively  to  the  foot-wall.  Fissures  formed  under 
such  conditions  cannot  yawn.  The  walls  must  come  together  at  intervals 
and  the  intervening  spaces  must  be  filled  to  a  greater  or  less  extent  with 
the  fragments  of  wall  rock.  Observation  shows  that  veins  very  usually 
answer  to  this  description  and  that  the  space  really  occupied  by  ore  corre- 
sponds in  great  part  to  the  interstices  between  fragments  of  wall  rock  which 
loosely  filled  the  fissure  before  the  ore  was  deposited.  This  is  observed 
with  particular  frequency  in  large  veins,  while  small  ones  are  comparatively 
free  from  rock  fragments  Irregular  ore  bodies  connected  with  fissures  still 
more  often  represent  masses  of  rock  fragments  rather  than  caverns. 

In  some  cases  irregular  chambers  connected  with  fissures  are  solidly 
filled  with  ore  and  gangue  minerals.  Such  bodies  are  found  in  limestones 
under  conditions  which  preclude  the  supposition  that  they  represent  pre- 
existing caverns,  and  they  are  usually  accompanied  by  evidences  of  sub- 
stitution of  ore  for  carbonate  of  lime.  The  deposits  of  Eureka  and  of 
Leadville  are  of  this  type.  In  these  cases  broken  rock  seems  originally  to 
have  filled  the  spaces  in  question,  much  as  stopes  in  mines  are  often  filled 
with  rock  by  miners  to  prevent  their  collapse  after  the  removal  of  the  ore. 
Solutions  of  ore  finding  access  to  these  spaces  through  the  main  fissures 
have  come  in  contact  with  very  extensive  surfaces  of  limestone.  The  lime- 
stone has  been  dissolved  and  ore  has  replaced  the  rock  molecule  for  mole- 
cule. Whether  similar  substitution  occurs  in  other  rocks  than  limestone 
and  with  other  ores  than  those  of  lead  has  not  been  sufficiently  investi- 
gated. 

Fissures  in  the  earth's  mass  would  extend  indefinitely  both  laterally 
and  vertically  if  the  rocks  possessed  neither  plasticity  nor  elasticity.  No 
rocks,  however,  are  devoid  of  either  of  these  properties.  It  is  well  known, 
accordingly,  that  fissures  are  not  of  indefinite  length.  They  sometimes 


VEINS.  409 

pass  over  into  folds,  as  several  geologists  have  pointed  out;  and  even  in 
granite  areas  dikes  of  eruptive  rock  may  sometimes  be  observed  which, 
diminish  gradually  in  width  to  a  fine  edge  and  disappear.  There  is  every 
probability  that  fissures  also  die  out  in  depth  in  a  similar  manner,  though 
where  considerable  faults  have  occurred  the  depth  of  a  fissure  must  be  very 
great.  Many  fissures  certainly  penetrate  from  the  surface  of  the  earth  to 
the  foci  of  volcanic,  activity,  a  depth  probably  at  least  equal  to  that  at 
which  earthquake  shocks  originate,  or  several  miles  from  the  surface. 

Simple  veins,  parallel  veins,  and  linked  veins. WllCll    tllC    tCHl!    fisSlU'C    Veill    Is    UScd 

without  any  qualification,  it  brings  to  mind  a  very  simple  and  common 
form  of  deposit:  a  fissure  with  well  defined  walls  usually  nearly  straight 
or  curving  gradually  and  including  vein  matter  which  is  commonly  com- 
posed of  ore,-  gangue,  and  fragmentary  masses  of  country  rock.  A  vertical 
section  of  such  a  vein  is  shown  below  (see  Fig.  20  a).  It  appears  to  me  very 
desirable  not  only  to  call  a  deposit  of  this  kind  a  simple  fissure  vein,  but  to 
limit  the  application  of  this  term  to  deposits  of  this  kind.  It  is  not  diffi- 
cult to  find  natural  designations  for  allied  but  less  regular  deposits. 

Where  the  formation  of  a  fissure  is  accompanied  by  a  strong  compress- 
ive  stress  groups  of  parallel  fissures  form,  often  passing  over  into  a  com- 
mon fold  at  each  end.  The  dislocation  is  then  distributed  over  a  number 
of  parallel  surfaces  instead  of  a  single  surface,  and  this  distribution  takes 
place  according  to  a  definite  law,  which  I  have  examined  on  other  occa- 
sions.1 In  some  cases  such  fissures  form  with  great  regularity  and  are  dis- 

• 

tinct  from  one  another  as  far  as  they  can  be  traced.  If  ore-bearing  solu- 
tions enter  such  ground,  they  deposit  distinct,  parallel  veins.  Such  deposits 
are  naturally  described  as  groups  of  parallel  veins. 

In  many  cases  a  tendency  to  the  formation  of  groups  of  parallel  fis- 
sures is  obstructed,  perhaps  by  irregularities  in  the  tenacity  of  the  rock  or 
by  the  action  of  complex  forces.  In  such  instances  approximately  parallel 
fissures  form,  which  die  out  in  the  direction  of  their  strike,  being  replaced 
by  others  to  one  side  or  the  other.  More  or  less  diagonal  stringers  must 
then  exist,  connecting  the  principal  crevices.  Sometimes  fissures  of  this 

1  Geology  of  the  (Vmslork  I/mle   (Miiijytc.r  IV;    Impact,  friction,  anil  faulting:  Am.  Jour.  Sci.,  3d 
series,  vol.  HO,  1885. 


410 


QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 


kind  run  together  and  separate  again,  without,  however,  diverging  at  any 
high  angle.1     Plans  of  such  groups  of  veins  are  shown  in  Fig.  19. 


FIG.  19.   Linked  veins ;  horizontal  section. 

In  all  cases  these  veins  are  linked  together  by  direct  continuations  of 
divergent  strike  or  by  small  stringers  intersecting  the  layers  of  rock  which 
intervene  between  them.  It  appears  to  me  convenient  and  natural  to  call 
such  systems  linked  veins,  to  distinguish  them  from  simple  fissure  veins  and 
parallel  systems  of  veins  on  the  one  hand  and  from  netted  (or  reticulated) 
veins  on  the  other. 

There  are  still  other  less  usual  groupings  of  veins  which  do  not  need 
to  be  christened.  No  one  would  hesitate  to  speak  of  a  system  of  veins 
which  radiated  from  a  central  point  as  radiating  veins  or  of  a.  vein  which 
sends  off  numerous  stringers  into  the  country  rock  as  a  branching  vein, 
and  such  descriptive  terms  are  clear  and  precise. 

chambered  veins — A  slight  degree  of  irregularity  in  the  tenacify  of  the 
rocks  or  in  the  character  of  the  rupturing  force  suffices  to  produce  linked 
fissures  instead  of  groups  of  parallel  fissures.  Greater  variations  in  the 
rock  or  a  torsional  stress  accompanying  the  dislocation  will  result  in  crush- 
ing portions  of  the  country  rock  adjacent  to  the  main  fissure  This  crush- 

1  Either  a  group  of  veins  occupying  fissures  of  this  description  or  a  system  of  parallel  veins  is  culled 
in  German  a  Gnngzug,  lint  this  word,  though  short  and  expressive,  has  no  Knjjlish  equivalent  and  is 
not  readily  translated  by  any  concise  term.  II  means  a  procession  or  a  flight  of  veins.  It  might  be 
possible  to  introduce  the.  term  a  ncliinil  of  veins,  us  we.  speak  of  a  school  of  lish,  but  the  metaphor  dues 
not  seem  particularly  worth  preserving. 


VEIXS. 


411 


ing  will  not  as  a  rule  bo  confined  to  a  simple  zone  parallel  with  the  fissure, 
but  will  reduce  only  occasional  masses  of  rock  along  the  fissure  to  frag- 
ments. When  in  such  cases  ore  and  gangue  minerals  are  subsequently 
precipitated,  the  deposit  will  be  confined  to  the  main  fissure  where  the 
adjoining  country  is  unbroken,  but  it  will  spread  into  the  neighboring  rock 
where  crushing  has  occurred,  the  excrescent  ore  bodies  being  nevertheless 
merely  lateral  extensions  of  the  filling  of  the  fissures.  Miners  then  usiiiillv 
call  the  entire  occurrence  a  fissure  vein,  and  with  no  little  reason,  since  the 
\vliolc  deposit  is  so  evidently  and  closely  dependent  upon  the  existence  of 
a  fissure.  In  some  of  the  simpler  cases  of  this  kind  even  formalists  will 
grant  the  applicability  of  such  a  term  as  irregular  vein  or  vein  with  irreg- 
ular walls.  "Pipe  vein"  has  also  sometimes  been  used  to  express  structure 
of  this  kind,  but  this  term  has  been  employed  in  such  various  senses  as  to 
be  objectionable.  When  the  irregularity  of  the  deposits  is  great,  it  has 
been  usual  for  mining  engineers  and  geologists  to  describe  rather  than  to 
name  them,  to  speak  of  stock\vorks  and  impregnations  connected  with 
veins,  and  the  like.  It  does  not  seem  expedient,  however,  to  designate  ore 
bodies  so  very  closely  related  by  different  names  unless  the  connection  is 
also  expressed  by  some  appropriate  term.  The  connection  existing  between 
the  various  portions  of  a  deposit  is  at  least  as  important  as  the  form  of  the 
various  parts,  and,  if  miners  err  in  giving  a  wrong  impression  as  to  form, 
the  usual  nomenclature  of  mining  geologists  ignores  the  close  interdepend- 
ence recognized  in  the  language  of  the  miners. 


Fir,.  20.   Simple  fissure  vein  and  chamlirml  vein. 


The  form  of  deposit  under  discussion  is  illustrated  in  the  above  dia- 
gram (Fig.  20  fc). 


412  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

It  seems  to  me  that  deposits  of  this  description  may  conveniently 
be  called  c.Jt  a  inhered  veins  and  that  the  irregular,  excrescent  bodies  of  ore 
of  such  deposits  may  fitly  be  denominated  vein  <'Iin»tht'rx.  I  propose  these 
terms  to  express  the  external  form  only  and  to  embrace  irregular  ore 
bodies  contiguous  with  a  fissure,  whether  they  consist  of  reticulated 
masses,  of  impregnations,  or  ore  deposited  by  substitution.  A  chambered 
vein  may  then  be  defined  as  a  deposit  consisting  of  an  ore-bearing  fis- 
sure and  of  ore  bodies  contiguous  with  the  fissure  .which  extend  into  the 
country  rock.  The  term  is  intended  for  use  in  contradistinction  to  the  term 
fissure  vein,  or,  more  explicitly,  simple  fissure  vein,  which  is  thus  restricted 
to  those  cases  in  which  the  occurrence  of  ore  is  limited  to  a  single  defined 
fissure.  Transitions  between  the  two  forms  are  not  infrequent,  and  such 
occurrences  may  be  referred  to  conveniently  as  veins  which  are  to  some 
extent  chambered  or  which  show  a  tendency  to  chambering.1 

cap  chambers — In  granites  and  gneisses  it  is  not  infrequently  the  case  that 
simple  fissure  veins  are  found  which  from  the  cropping  downward  are  very 
regular.  I  doubt,  however,  whether,  if '  in  these  cases  the  surface  still  re- 
mained as  it  existed  at  the  time  when  the  fissure  was  formed,  the  superior 
portion  of  the  deposits  would  be  found  to  possess  an  equal  degree  of  regu- 
larity. When  a  fissure  is  formed  a  fault  almost  or  quite  invariably  accom- 
panies it,  for  it  is  a  force  tending  to  elevate  one  portion  of  a  region  above 
another  which  usually  produces  the  fissure.  When  a  fault  takes  place,  it  is 
well  known  that  the  hanging  country  is  commonly  depressed  relatively  to 
the  foot-wall  and  a  projecting  edge  of  the  hanging  ground  must  then  press 
and  scrape  against  the  foot-wall.  This  wedge  like  mass,  not  being  sup- 
ported at  the  surface  by  overlying  rock,  is  greatly  exposed  to  fracture,  and 
will  generally  be  more  or  less  fissured,  even  when  it  is  composed  of  firm 
material,  such  as  granite.  If  ore  deposition  follows  from  solutions  which 
reach  the  upper  part  of  such  a  fissure,  the  irregular  cracks  in  the  lip  of  the 
hanging  country  will  fill  with  vein  matter  and  the  simple  vein  will  be  sur- 
mounted by  a  chamber  or  a  series  of  chambers  close  to  the  surface. 

'"Chambere'l  veins"  seems  lo  be  ;is  natural  anil  as  appropriate-  a  term  MS  tin1  familiar  "rliainliereil 
slicll;"  indeed,  the  analogy  between  them  is  a  close  one,  for  the  siphunelo  which  passes  through  the 
chambers  of  the  nautilus  anil  of  other  tetrabra:ioliiata  answers  to  the  fissure  of  a  chambered  vein. 


VEINS.  413 

If  a  country  be  composed  of  rock  of  feeble  and  variable  tenacity,  the 
tendency  of  the  ground  near  the  surface  to  break  up  into  irregular  frag- 
ments will  be  much  greater  than  where  the  country  is  firm  and  homogene- 
ous, and  the  formation  of  chambers  of  OTe~  close  to  the  original  surface  is 
the  more  to  be  expected.  The  ore  bodies  which  were  found  near  the  crop- 
pings  of  the  Comstock  Lode  were  of  this  description,  and  so  are  most  of 
the  more  superficial  cinnabar  deposits  of  California. 

I  propose  for  these  irregular  bodies  found  at  the  croppings  of  veins 
the  name  cap  chambers,  to  distinguish  them  from  the  lateral  ore  bodies  of 
chambered  veins.  The  term  vein  chamber  then  includes  cap  chambers  as 
well  as  lateral  chambers. 

So  far  as  we  know  anything  of  the  mechanical  conditions  of  ore  depo- 
sition, it  appears  from  the  foregoing  paragraphs  that  many  deposits  which 
now  appear  as  simple  fissure  veins  must  once  have  included  cap  chambers, 
and  must  consequently  have  come  under  the  definition  which  I  have  pro- 
posed of  a  chambered,  vein.  The  cap  chambers  in  these  cases  must  have 
been  removed  by  erosion.  Where  ore  deposition  has  continued  until  all 
available  crevices  were  filled,  as  has  sometimes  but  not  always  been  the 
case,  it  is  evident  that  cap  chambers  will  contain  a  comparatively  large 
amount  of  ore,  often  more  than  will  be  found  within  an  equal  vertical  inter- 
val far  from  the  surface,  where  the  fissure  system  is  more  simple.  Such 
was  the  case,  for  example,  on  the  Comstock  lode.  Such  also  may  have  been 
the  case  on  the  gold  belt  of  California,  and  the  immense  amount  of  aurifer- 
ous gravel  would  then  not  represent  the  erosion  of  contracted  quartz  veins, 
such  as  are  now  being  mined,  but  of  the  cap  chambers  of  the  veins.  This 
hypothesis  greatly  reduces  the  amount  of  general  erosion  which  the  exist- 
ence of  these  gravels  would  imply. 

The  terms  simple  fissure  vein,  group  of  parallel  veins,  linked  veins,  and 
chambered  veins  probably  include  nearly  all  species  of  deposits  except- 
ing sedimentary  beds  and  placers.  It  is  of  course  easy  to  imagine  irregu- 
lar bodies  of  ore  unconnected  with  any  fissure  system,  but  it  is  doubtful 
whether  such  really  occur  in  nature.  If  these  terms  should  be  adopted,  the 
names  impregnation,  stockwork,  pocket,  etc.  would  be  understood  to  refer 
only  to  the  structural  character  of  specific  portions  of  deposits,  and  not  to 
the  form  of  any  deposits  as  a  whole. 


414  QUICKSILVER  DEPOSITS  OF  TUB  PACIFIC  SLOPE. 

Formation  of  fissures  at  great  depths. — "While  it  appears  that  even  veins  in  firm, 
homogeneous  rock  must  tend  to  irregularity  near  the  original  surface  as  it 
existed  when  the  fissure  formed,  it  is  evident  that  at  great  depths  fissures  in 
irregular  and  weak  rocks,  such  as  those  which  form  the  greater  part  of  the 
Coast  Ranges,  must  tend  to  regularity  and  simplicity;  for  at  great  depths  the 
walls  of  a  fissure  are  so  supported  by  the  overlying  masses  that  even  if  the 
country  is  composed  of  discrete  fragments  these  will  be  held  in  place  very 
much  as  if  the  material  were  continuous.  Hence,  at  considerable  depths 
distinct  fissures  are  to  be  looked  for  even  in  the  quicksilver  mines  ;  but  it 
is  evident  that  the  mutual  support  of  fragmentary  rocks  will  act  only  so 
long  as  the  fissures  are  very  narrow.  If  considerable  openings  form,  such 
as  are  suitable  for  the  deposition  of  ore  in  large  masses,  irregular  reticuhited 
vein  chambers  will  result  in  such  material  at  any  depth.  In  such  rock  as 
I  have  seen  in  the  quicksilver  mines  of  California,  wide,  simple  fissure  veins 
are  not  to  be  expected  at  any  level  and  irregular  chambers  are  not  so  likely 
to  be  met  with  at  great  depths  as  at  small  ones,  though  they  may  occasion- 
ally be  found  at  any  distance  from  the  surface. 

Fissure  systems  at  the  various  mines. SillCC    fisSUl'e    SySteillS    ai'O     allBOSt    MeCeSSa- 

rily  more  simple  at  considerable  depths  than  near  the  surface,  there  is, 
a  priori,  a  strong  probability  that  veins  underlie  Sulphur  Bank  and  Steam- 
boat Springs.  As  to  the  extent  of  such  probable  veins  one  can  now  judge 
only  from  the  amount  of  water  which  seems  to  have  issued  from  them,  and 
this  is  but  a  poor  guide.  They  might  or  might  not  repay  the  expense  of 
the  explorations  necessary  to  discover  them.  At  Steamboat  the  springs 
rise  in  lines  approximately  parallel  to  the  trend  of  the  Sierra,  and  this  is 
also  the  probable  direction  of  the  underlying  fissures.  At  Sulphur  Bank 
there  is  no  certain  indication  of  a  prevailing  strike,  the  local  structure  being 
very  complex. 

What  seem  inevitable  conclusions  from  these  very  simple  principles  at 
these  active  springs  are  established  certainties  at  other  localities.  The  lied- 
ington  mine  has  been  shown  in  the  foregoing  discussion  to  be  closely  anal- 
ogous to  Sulphur  Bank  both  in  the  .method  of  genesis  indicated  and  in  its 
structural  features.  Near  the  surface  lay  the  irregular  bonanza,  answering 
to  the  lower  deposits  of  Sulphur  Bank.  A  few  hundred  feet  below  the  sur- 


VEIX  STRUCTURE  OF  VARIOUS  MINES.  415 

face  this  cap  chamber  was  connected  with  a  system  of  three  parallel  fissures, 
two  of  them  carrying  ore  and  being  in  fact  well  developed  and  unmistak- 
able chambered  veins.  Their  contents  varied  in  value  from  point  to  point, 
as  that  of  all  veins  does,  but  they  have  -yielded  large  quantities  of  ore. 
The  third  fissure  has  been  proved  to  exist,  but  at  the  one  point  where  it- 
was  intersected  it  carried  only  pyrite  and  no  ore.  In  the  main  mine  at 
New  Almadeu  there  exist  two  parallel  fissures  separated  from  each  other 
by  but  a  short  distance.  Ore  is  deposited  in  and  near  them,  so  that  they 
are  true  chambered  veins.  From  the  lower  levels  they  ascend  on  different 
courses  and  reach  the  surface  at  a  considerable  distance  from  each  other.  A 
great  wedge  of  country  rock  is  included  bet  ween  them,  and  fissures  attended 
by  ore  penetrate  this  also,  forming  chambered  branches  of  the  main  veins. 
But  perhaps  the  finest  and  most  interesting  examples  of  vein  structure  are 
afforded  by  the  group  of  mines  near  ^Etna  hot  springs,  which  issue  from 
one  of  them,  while  two  others  lie  at  the  contact  between  basalt  dikes  and 
the  inclosing  sedimentary  rocks.  As  was  noted  above,  there  is  no  reason 
to  suppose  that  this  group  of  adjoining  deposits  owes  its  origin  to  various 
causes;  indeed,  the  supposition  that  they  did  so  would  be  nothing  less  than 
extravagant.  Here  the  bodies  adjoining  and  in  part  penetrating  the  dikes 
are  unquestionably  chambered  veins,  but  still  more  striking  are  those  in 
the  main  workings  of  the  Napa  Consolidated  mine  at  Oathill,  called  the 
Mercury  vein  and  the  Manzanita  vein.  These  occupy  nearly  parallel  fault 
fissures  in  nearly  horizontal  unaltered  sandstones.  The  faulting  was  accom- 
panied by  compressive  stress,  as  is  proved  by  the  flexure  of  the  strata  in 
opposite  directions  near  the  fissures,  and  the  two  principal  fissures  were 
doubtless  produced  at  the  same  time.  Parts  of  these  veins  are  simple 
fissures  filled  with  vein  matter,  which  does  not  extend  beyond  the  walls, 
but  at  a  number  of  points  impregnation  of  the  adjacent  sandstone  has  taken 
place.  As  a  whole,  therefore,  these  deposits,  too,  are  to  be  classed  as  cham- 
bered veins.  The  upper  portion  of  the  Phoenix  seems  to  have  been  a  cap 
chamber,  and  this  is  the  character  of  most  of  the  smaller  deposits  in  the 
State.  The  Great  Eastern  and  the  Great  Western  are  both  chambered 
veins,  and  no  better  example  of  this  form  of  deposit  could  be  given  than 
'the  Elva-n  Streak  of  New  Idria. 


416  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

CONCLUSIONS. 
Conclusion  as  to  character  ol  deposits. TllG     many    analogies     of     tllO    VanOUS     Or6 

deposits  thus  point  to  a  common  origin  of  the  ores,  viz,  precipitation  in  fis- 
sures from  ascending  hot  solutions.  In  the  following  chapters  it  will  also 
be  shown  that  the  derivation  of  the  ores  is  inexplicable  except  upon  the  sup- 
position that  the  solutions  ascended  in  a  heated  state.  Portions  of  many  of 
the  deposits  can  only  be  described  by  themselves  as  simple  fissure  veins, 
and  the  existence  of  fissures  is  evident  in  all  of  them.  The  prevailing  type 
of  deposit  in  the  deeper  mines  is  the  chambered  vein,  where  the  chambers 
are  sometimes  reticulated  masses  and  sometimes  impregnations.  The  ore 
often  follows  the  bedding  for  a  certain  distance  and  such  portions  of  the 
deposits  are  bedded  veins. 

Cap  chambers  are  frequent  arid  in  many  cases  contain  most  of  the  ore. 
Stockworks  without  a  known  immediate  connection  with  chambered  veins 
have  been  met  in  some  mines,  but  these  are  probably  in  every  case  cham- 
bered branches  of  veins.  Of  all  the  principal  types  of  ore  deposits,  .substi- 
tuted masses  alone  seem  to  be  absent.  The  quicksilver  deposits  of  the 
Coast  Ranges  are  on  the  whole  more  irregular  than  the  deposits  of  average 
ores  in  other  regions.  This  is  due  to  the  heterogeneity  of  the  rocks  in  which 
they  occur;  but  irregularities  of  precisely  the  same  kind  are  found  in  veins 
of  other  metallic  ores  the  world  over  and  no  fundamental  distinction  exists 
between  deposits  of  cinnabar  and  deposits  of  other  metals. 

Age  of  inclosing  rocks. — The  greater  number  of  the  productive  mines  have  ex- 
tracted their  ore  from  chambers  in  rocks  of  Neocomian  age.  This  fact  dot's 
riot  seem  to  be  due  to  any  precipitating  influence  of  these  rocks,  which,  when 
unaltered,  are  of  exactly  the  same  composition  as  the  Tertiary  beds.  Still 
less  does  the  association  indicate  great  antiquity  for  the  deposits.  The  main 
lines  of  disturbance  in  California,  as  elsewhere,  are  marked  by  ranges,  and 
these  are  for  the  most  part  considerably  eroded.  In  consequence,  the  older 
strata,  where  they  have  once  been  covered  by  Post-Neocomian  rocks,  have 
been  re-exposed  along  the  old  axes  of  compression.  Renewed  movements 
always  tend  to  follow  the  old  lines,  and  thus  the  fissures  and  ore  deposits, 
though  of  comparatively  very  recent  date,  are  found  most  abundantly  in  the 
earliest  sedimentary  rocks  of  the  region.  The  physical  character  of  the  rock 


CONCLUSIONS.  417 

often  seems  to  influence  the  deposition  of  the  ore.  Cinnabar  occurs  along 
faulted  surfaces  in  wholly  unaltered  Neocomian  rocks,  but  this  is  rarely  the 
case.  Unchanged  sandstones  and  shales  are  more  likely  to  be  distorted  than 
to  break,  while  the  metamorphosed  rocks  are  brittle  and  are  intersected  by 
innumerable  partially  cemented  cracks.  Adjoining  masses  of  metamorphosed 
and  unaltered  rocks  will  present  different  amounts  of  resistance  to  disloca- 
tion, and  a  tendency  to  the  formation  of  fissures  is  most  likely  to  manifest 
itself  near  the  junction  of  such  areas.  Knoxville  and  New  Idria  are  excel- 
lent examples  of  this  fact,  which  it  is  worth  the  while  of  prospectors  to  note. 
Of  course  it  does  not  debar  the  formation  of  fissures  in  extensive  metamor- 
phosed areas. 

Relations  of  deposits  to  volcanic  rocks. — The  relation  of  the  quicksilver  deposits  to 
volcanic  rocks  is  indirect,  yet  close.  The  ore  deposition  seems  to  have  been 
immediately  dependent  upon  the  existence  of  hot  sulphur  springs,  which 
were  probably  in  all  cases  of  volcanic  origin.  Such  springs  are  most  likely 
to  occur  at  a  very  moderate  distance  from  lava,  but  this  is  no  invariable  rule, 
several  miles  sometimes  separating  such  springs  from  the  nearest  volcanic 
vents.  So  far  as  is  known,  basalt  is  the  lava  usually  associated  with  the  de- 
posits, but  the  most  important  series  of  deposits  in  the  State  seems  to  have 
been  induced  by  a  rhyolite  eruption.  Some  little  deposits  of  cinnabar  exist 
in  andesite,  and  it  is  possible  they  are  due  to  hot  springs  following  the  erup- 
tion of  this  rock.  Some  other  deposits  are  also  nearer  to  andesites  than  to 
basalts.  I  know  of  no  reason  to  doubt  that  cinnabar  deposits  were  formed 
by  springs  which  owed  their  temperature  and  composition  to  volcanic  activity 
of  the  andesitic  period,  but  I  have  no  unquestionable  evidence  that  this  was 
the  case. 

Age  of  the  ore  deposits — So  far  as  is  known,  volcanic  activity  in  the  Coast 
Ranges  began  in  the  Pliocene,  and  the  main  outbursts  of  the  andesite  seem 
to  have  closed  that  period.  The  age  of  the  cinnabar  deposits  is,  then,  lim- 
ited to  Post-Miocene  times,  and  there  is  little  doubt  that  nearly  all  the  ore 
has  been  deposited  since  the  end  of  the  Pliocene. 

Future  of  quicksilver  mining. —  I  cannot  say  that  tlie  future  of  the  quicksilver 
industry  on  the  Pacific  slope  seems  to  me  very  hopeful.  The  trouble  is  not 
MON  xni 27 


418  QUIOKS1LVEK  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

in  the  lack  of  cinnabar,  but  in  the  mechanical  disintegration  of  the  country 
effected  by  the  Post-Neocomian  upheaval.  To  this  are  due  the  great  irreg- 
ularity of  the  deposits,  the  dissemination  of  cinnabar  in  minute  fissures,  or 
as  "paints,"  in  the  language  of  miners,  and  the  small  average  size  of  the 
deep-seated  veins.  Deposits  may  somewhere  be  found  in  firmer  or  less  fis- 
sured rock,  but  there  only  can  strong,  simple  fissure  veins  be  expected  to 
prevail  in  depth.  Such  deposits  are  exceptional  everywhere.  In  the  Al- 
maden  district  ore  is  known  to  occur  at  over  seventy  points,  but  at  only  one 
of  them  was  the  accumulation  great  enough  to  supply  the  world  with  mer- 
cury for  thousands  of  years.  The  Santa  Barbara,  at  Huancavelica,  too,  was 
one  of  over  forty  known  deposits  in  the  same  district.  Systematic  and  in- 
telligent prospecting  is  even  more  needful  in  mines  on  the  Coast  Ranges 
of  California  than  elsewhere,  and  the  special  attention  of  superintendents 
should  be  directed  to  a  study  of  the  fissure  system.  This  will  almost  in- 
variably be  very  complex,  and  can  be  satisfactorily  made  out  only  by  daily 
study  as  the  work  progresses.  When  a  large  part  of  the  mine  is  abandoned 
and  closed,  it  is  often  impossible  to  find  the  key  to  the  true  distribution  of 
the  fissures  and  of  the  ore  chambers  which  accompany  them.  Helpless 
groping,  discouragement,  and  often  the  abandonment  of  property  which 
probably  contains  treasures  often  follow.  An  increase  of  geological  skill 
in  the  management  of  quicksilver  mines  would  do  much  to  offset  the  unfor- 
tunately capricious  distribution  of  ore.  Good  civil  and  mechanical  engi- 
neering is  necessary,  but  not  sufficient,  to  make  the  best  of  a  quicksilver 
mine,  nor  can  occasional  assistance  supply  the  place  of  enlightened  daily 
study  of  geological  structure.  There  is  nothing  novel  in  this  warning,  nor  is 
there  any  probability  that  so  trite  a  piece  of  common  sense  will  be  heeded. 


CHAPTER  XV. 

ON  THE  SOLUTION  AND  PRECIPITATION  OF  CINNABAR 

AND  OTHER  ORES.1 

The  waters  of  Steamboat  Springs  are  now  depositing  gold,  probably 
in  the  metallic  state;  sulphides  of  arsenic,  antimony,  and  mercury;  sul- 
phides or  sulphosalts  of  silver,  lead,  copper,  and  zinc ;  iron  oxide  and  pos- 
sibly also  iron  sulphides;  and  manganese,  nickel,  and  cobalt  compounds, 
with  a  variety  of  earthy  minerals.  The  sulphides  which  are  most  abun- 
dant in  the  deposits  are  found  in  solution  in  the  water  itself,  while  the  re- 
maining metallic  compounds  occur  in  deposits  from  springs  now  active  or 
which  have  been  active  within  a  few  years.  These  springs  are  thus  actu- 
ally adding  to  the  ore  deposit  of  the  locality,  which  has  been  worked  for 
quicksilver  in  former  years  and  would  again  be  exploited  were  the  price 
of  this  metal  to  return  to  the  figure  at  which  it  stood  a  few  years  since. 
At  Sulphur  Bank  also  ore  deposition  is  still  in  progress,  but  under  condi- 
tions which  differ  somewhat  from  those  presented  at  Steamboat  Springs. 
The  waters  of  the  two  localities  arc  closely  analogous.  Both  contain  so- 
dium carbonate,  sodium  chloride,  sulphur  in  one  or  more  forms,  and  borax 
as  principal  constituents,  and  both  are  extremely  hot,  those  at  Steamboat 
Springs  in  some  cases  reaching  the  boiling-point.  The  water  of  Sulphur 
Bank  is  ammoniacal.  In  attempting  to  determine  in  what  forms  the  ores 
enumerated  can  be  held  in  solution  in  such  waters,  it  is  manifestly  expe- 
dient to  begin  by  studying  the  simplest  possible  solutions  of  the  sulphides, 
and  particularly  of  cinnabar. 

previous  investigations. — The  solubility  of  mercuric  sulphide  in  alkaline  com- 
pounds containing  sulphur  has  long  been  recognized  by  experimental  and 

'  A  digest  of  this  chapter  appeared  iu  the  Am.  Jour.  Sui.,  3d  series,  vol.  :i:t,  1887,  p.  l!i:i. 

419 


420  QUICKSILVER  DEPOSITS  OF  TQE  PACIFIC  SLOPE. 

industrial  chemists.  This  fact  is  the  foundation  of  the  methods  of  prepa- 
ration of  vermilion  in  the  wet  way,  first  described  by  G.  S.  C.  Kirchhoff 
in  1799.1  In  1829  C.  Brunner2  discovered  the  double  soluble  salt  HgS, 
K2S  +  5H20.  Later,  Dr.  Reinhardt  Weber3  re-examined  the  properties  and 
formation  of  this  salt,  which  he  found  could  only  exist  in  the  presence  of 
free  caustic  alkali.  In  opposition  to  Professor  Stein,  Dr.  Weber  is  extremely 
positive  in  his  statement  that  mercuric  sulphide  is  entirely  insoluble  either 
in  the  simple  sulphides  of  sodium  and  potassium  or  in  the  sulphydrates  of 
these  metals,  excepting  in  the  presence  of  free  hydrates.  In  the  light  of 
facts  definitely  ascertained  since  this  chemist's  investigation,  so  general  a 
statement  does  not  seem  to  be  borne  out  by  his  own  observations;  for  he 
says  that  if  potassic  hydrate  be  added  to  the  sulphydrate  the  mixture  dis- 
solves mercuric  sulphide  with  the  greatest  ease.  Now,  excepting  when  ex- 
tremely dilute,  a  mixture  of  the  two  alkaline  solutions  produces  potassic 
protosulphide,  K2S,  and,  unless  more  caustic  potash  was  added  than  would 
be  sufficient  to  convert  all  the  sulphydrate  into  the  simple  sulphide,  Dr. 
Weber's  solution  was  not,  as  he  evidently  supposes,  a  mixture  of  hydrate 
and  sulphydrate,  but  of  simple  sulphide  and  sulphydrate. 

In  1864  Mr.  C.  T.  Barfoed4  investigated  the  behavior  of  mercuric 
sulphide  to  sodium  sulphides.  He,  like  Dr.  Weber,  found  the  metallic 
sulphide  wholly  insoluble  in  the  sulphydrate,  but  soluble  in  the  simple  sul- 
phide, and  in  mixtures  of  the  latter  either  with  the  sulphydrate  or  with  the 
hydrate.  He  insists  that  the  necessary  and  sufficient  condition  for  the  sol- 
ubility of  mercuric  sulphide  is  the  presence  of  sodic  protosulphide. 

The  assertion  is  frequently  made  in  chemical  writings,5  in  spite  of  the 
results  obtained  by  Weber  and  by  Barfoed,  that  mercuric  sulphide  is  solu- 
ble in  sodium  sulphydrate;  but,  though  Professor  Stein  and  the  other  chem- 
ists who  have  made  this  assertion  may  not  have  employed  fully  saturated 
sulphydrate,  as  will  appear  later,  none  of  them  can  have  failed  to  carry  the 
saturation  beyond  50  per  cent ,  and  none,  therefore,  can  have  dealt  with 

1  Allg.  Jour,  tier  Chcmio,  Scberer.  vol.  2,  p.  290. 

•-•  1'ojjgendorff,  Anualcu,  vol.  15,  i>.  593. 

3  Ibid.,  4th  series,  vol.  7,  l-.~>(>,  p.  7(1. 

« Jour,  prakt.  Chemie,  vol.  9:5,  1864,  p.  2:30. 

6  For  example,  Graham-Otto,  fifth  edition,  part  3,  vol.  2,  p.  111!). 


s 


SOLUTION  OF  CINNABAR,  421 

mixtures  containing-  free  hydrate.  A  probable  explanation  of  this  apparent 
neglect  of  careful  investigations  will  appear  a  little  further  on.  In  1876 
Mr.  M.  C.  Mt'hu1  examined  the  soluble,  crystalline  mercury-sodium  salt  cor- 
responding to  Brunner's  potassium  compound.  He  found  mercuric  sulphide 
insoluble  in  sodic  hydrate  or  in  the  simple  sulphide  of  sodium,  but  highly 
soluble  in  mixtures.  One  part  of  mercuric  sulphide  with  two  parts  of  the 
crystallized  sulphide  of  sodium  and  two  parts  of  a  solution  of  sodic  hydrate 
of  specific  gravity  1.33  form,  he  found,  a  perfect  fluid,  which  absorbs  car- 
bonic acid  and  gradually  precipitates  at  first  sodium  carbonate  containing 
mercuric  sulphide  and  later  crystals  of  cinnabar. 

Alkaline  pentasulphides  convert  amorphous  quicksilver  sulphide  di- 
gested with  them  into  cinnabar,2  and  this  process  implies  a  certain  degree 
of  solubility.  Mr.  Barfoed,  however,  found  mercuric  sulphide  insoluble  at 
ordinary  pressures  in  sodium  sulphydrate  to  which  sulphur  had  been  added, 
and  the  solubility  in  the  pentasulphide  is  probably  slight.  The  conversion 
of  the  black  into  the  red  sulphide  does  not  appear  to  imply  more  than  a 
mere  trace  of  solubility,  for  Messrs.  IT.  Sainte-Claire  Deville  and  Debray 
produced  rhombohedral  crystals  of  cinnabar  by  heating  precipitated  sulphide 
with  chlorhydric  acid  to  100°  C.  in  a  closed  tube.3  No  statement  is  made  in 
the  account  of  this  experiment  of  any  means  being  employed  to  produce 
any  great  pressure.  Mr.  S.  B.  Christy4  found  that  at  pressures  of  from 
150  to  500  pounds  per  square  inch  and  temperatures  of  from  180°  to  200° 
various  liquids  heated  with  precipitated  mercuric  sulphide  convert  it  into 
vermilion.  He  experimented  with  polysulphides  of  potassium,  potassic 
sulphydrate,  acid  sodic  carbonate  charged  with  sulphydric  acid,  and  a 
spring  water  containing  acid^odic  carbonate  which  he  charged  with  sulphy- 
dric acid.  He  reached  no  conclusions  as  to  the  state  of  combination  of 
the  mercury  in  solution.  The  fact  that  glass  is  greatly  attacked  at  high 
pressures  and  temperatures  by  alkaline  solutions  of  course  leaves  many 
possibilities  open.  Prof.  H.  Wagner5  has  shown  that  mercuric  sulphide  is 

'Russian  Jour,  of  Phariu.,  reported  in  Jahresbericht  dor  Cliemie,  187t>,  p.  282. 

•Gmeliu-Krant:   Handlmcli  dor  Cheinio,  Anorganischo  Cheinie,  vol.3,  p.  758,  where  many  refer- 
ences may  be  found. 

"Fouqno"  and  Michel-LoVy  :  Syntliese  des  min.  et  dcs  roclics.  p.  31:!. 
<Ain.  Jour.  Sci.,  3d  sorios,  vol.  17,  1879,  p.  453. 
"Jour,  pnikt.  Clinnir,  vol.  !H,  18lifi,  p.  •->:',. 


422  QUICKSILVER  DEPOSITS  OF  TQE  PACIFIC  SLOPE. 

soluble  in  barium  sulphide  and  Professor  Roth1  thinks  it  probable  that  cal- 
cium sulphide  possesses  a  similar  power. 

soiuwiity  of  HgS  in  mixtures  of  Na's  and  NaoH. — A  series  of  experiments  was  made 
in  my  laboratory  with  a  view  of  testing  the  relative  effect  of  the  quantity 
of  sodium  sulphide  and  sodium  hydrate  on  the  quantity  of  mercuric  sulphide 
which  a  given  mixture  of  the  solvents  would  take  up.  It  is  almost  impos- 
sible to  make  experiments  of  this  kind  with  the  same  accuracy  which  can 
easily  be  attained  in  precipitations,  because,  if  one  or  more  drops  of  either 
fluid  reagent  be  added  to  a  mass  consisting  of  mercuric  sulphide  partially 
dissolved  in  the  menstruum,  it  is  not  practicable  to  say  how  long  a  time  will 
elapse  before  the  additional  drop  will  have  become  saturated.  Approximate 
results  are,  however,  readily  obtained,  and  these  appear  in  the  present  case 
to  be  sufficient. 

It  was  found  that,  provided  a  small  quantity  of  free  hydrate  exists  in 
the  mixture,  the  solubility  of  mercuric  sulphide  depends  upon  the  quantity 
of  sodium  sulphide  in  the  solution,  or,  in  other  words,  that,  if  to  a  mixture  of 
Na2S  and  NaOH  more  sodic  hydrate  be  added,  the  solvent  power  of  the  mixt- 
ure is  neither  increased  nor  diminished  thereby.  For  example,  three  solu- 
tions, containing,  respectively,  0.95,  1.38,  and  2.29  grains  of  sodic  hydrate, 
and  each  containing  almost  the  same  quantity  of  sodic  sulphide  (about  0.7 
gram),  each  dissolved  the  same  quantity  of  mercuric  sulphide.  A  very 
small  quantity  only  of  the  hydrate  is  sufficient  to  secure  to  the  alkaline 
sulphide  its  maximum  solvent  power  over  mercuric  sulphide.  The  greater 
part  of  the  experiments  made  to  test  the  maximum  solubility  of  HgS  in 
Na2S  in  the  presence  of  NaHO  shows  that  the  relation  of  the  weights  of 
the  two  substances  is  very  nearly  in  the  proportion  of  one  molecule  of  HgS 
to  two  molecules  of  Na2S.  The  average  of  fourteen  such  experiments  gives 
iHgS  to  2.03Na2S.  From  the  nature  of  the  experiments  a  slight  excess  in 
the  quantity  of  the  solvents  employed  is  to  be  expected.  One  experiment 
was  made  by  mixing  mercuric  and  sodic  sulphide  in  the  proportion  of  two 
molecules  of  the  latter  to  one  of  the  former  and  adding  a  few  drops  of  caus- 
tic soda.  A  mere  trace  of  the  metallic  sulphide  remained  undissolved  and 

1  Allg.  nnd  chem.  Geol.,  vol.  1,  187'J,  p.  204. 


SOLUBLE  SULPHOSALT  OF  MERCURY.  423 

this  completely  disappeared  on  the  addition  of  a  single  drop  of  a  solution 
of  alkaline  sulphide,  so  that  less  than  one  drop  completed  the  solution. 

Chemists,  of  course,  regard  cases  of  solution  such  as  that  under  dis- 
cussion as  due  to  the  genesis  of  soluble  double  salts,  which  are  formed 
according  to  ordinary  laws  of  composition.  The  above  experiments  show 
that  this  soluble  double  salt  can  be  represented  only  by  the  formula  HgS, 
2X;rS  and  that  it  is  soluble  in  dilute  caustic  soda. 

The  soluble  mixture  given  by  Mehu  appears  to  be  intended  to  repre- 
sent the  maximum  solubility  of  mercuric  sulphide,  for  he  states  that  sulphy- 
dric  acid  instantly  produces  a  precipitate  in  it.  As  previously  stated,  it  con- 
tains two  parts  of  crystallized  simple  sodic  sulphide  (Na2S,  9II20)  to  one 
of  IlgS,  which  .answers  to  HgS  +  2.07Na2S  and  is  thus,  so  far  as  it  goes, 
confirmatory  of  the  above  experiments. 

solubility  of  Hgs  in  Na's. — The  most  carefully  prepared  solutions  of  sodium 
sulphide  dissolve  mercuric  sulphide' freely.  This  statement  is  directly  con- 
trary to  that  which  some  of  the  chemists  referred  to  have  made,  and  it 
would  be  a  rash  one  if  the  evidence  to  be  adduced  for  it  depended  simply 

* 

upon  bringing  solutions  of  sodic  sulphide  into  contact  with  mercuric  sul- 
phide, for  it  is  impossible  to  make  certain  that  there  is  no  trace  of  free  caustic 
alkali  or  of  sulphydrate  in  solutions  of  Na2S,  however  closely  its  analy- 
sis may  correspond  to  its  theoretical  composition.  If,  however,  a  solution 
of  sodic  hydrate  be  treated  with  sulphydric  acid,  it  is  gradually  converted 
into  sodic  sulphydrate  and  passes  through  a  point  at  which  the  only  com- 
pound present  is  sodic  protosulphide.  If  mercuric  sulphide  be  dissolved  in 
a  mixture  of  sodic  sulphide  and  sodic  hydrate  and  the  clear  filtrate  treated 
with  hydrogen  sulphide,  the  mercuric  sulphide  begins  to.  be  precipitated 
when  very  little  free  caustic  alkali  is  left,  and  it  is  continuously  precipitated 
until  the  entire  amount  of  sodium  present  is  converted  into  the  sulphydrate. 
The  purest  preparations  of  sodic  sulphide  (Na2S)  which  we  have  been  able 
to  make,  dissolve  mercuric  sulphide  less  freely  than  mixtures  of  sodic  sul- 
phide and  sodic  hydrate,  but  more  freely  than  mixtures  of  sodic  sulphide 
and  sodic  sulphydrate.  Different  preparations,  however,  shown  by  most 
careful  analysis  to  correspond  very  accurately  to  the  formula  Na2S,  give 
somewhat  different  results,  possibly  indicating  a  minute  variation  from  ab- 


424  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPI*}. 

solute  purity.  It  does  not  seem  a  priori  improbable  that  the  soluble  salt 
when  the  sodic  sulphide  is  absolutely  pure  is  IlgS,  3Na2S,  and  one  of  our 
preparations  gave  almost  exactly  this  result.  It  may  also  be  that  the  mixt- 
ures of  HgS,  2Na2S  and  HgS,  4Na2S  are  formed  in  proportions  varying 
with  other  conditions  than  the  purity  of  the  sodium  sulphide,  such  as  tem- 
perature and  concentration. 

insolubility  of  Hgs  in  coid  NEKS. — Repeated  experiments  and  analyses  under- 
taken during  this  investigation  have  shown  that  mercuric  sulphide  is  totally 
insoluble,  in  sodic  sulphydrate  at  ordinary  temperatures  and  that  any  prep- 
aration of  this  compound  which  will  dissolve  a  trace  of  mercuric  sulphide 
can  be  shown  by  analysis  1o  fall  short  of  complete  saturation.  A  long  time 
and  an  enormous  quantity  of  hydrogen  sulphide  are  required  to  completely 
saturate  even  a  small  amount  of  caustic  soda  with  sulphur.  As  already 
mentioned,  both  Weber  and  Barfoed  were  aware  of  the  insolubility  of  mer- 
curic sulphide  in  sodic  sulphydrate  at  ordinary  temperatures.  It  will  be 
seen  later  that  the  behavior  of  these  compounds  varies  with  the  tempera- 
ture. If  mercuric  sulphide  be  left  in  contact  with  cold  sodium  sulphydrate 
for  twenty-four  hours,  just  a  trace  of  mercury  goes  into  the  solution.  This 
is  due  to  the  spontaneous  loss  of  hydrogen  sulphide  which  the  sulphydrate 
is  well  known  to  undergo. 

The  absolute  want  of  power  of  a  preparation  of  sodium  sulphydrate 
to  dissolve  a  trace  of  mercuric  sulphide  is  perhaps  the  best  known  test  of 
its  freedom  from  the  alkaline  protosulphide.  This  test  does  not  show  the 
absence  of  polysulphides,  however,  for  we  have  frequently  found  mercuric 
sulphide  totally  insoluble  in  solutions  of  sodic  sulphydrate  which  possessed 
a  yellow  color  and  which  were  proved  by  analysis  to  contain  an  excess  of 
sulphur.  This  corresponds  to  Barfoed's  observation.  The  occurrence  of 
alkaline  polysulphides  in  nature,  excepting  near  the  surface  of  the  earth, 
seems  so  improbable  that  I  have  undertaken  no  investigations  of  the  con- 
ditions under  which  they  dissolve  mercuric  sulphide. 

Solubility  of  HgS  in  mixtures  of  Na^S  and  Na'S,  H'S. For  tll6  pUl'pOSB  of    determining 

the  character  of  solutions  of  mercuric  sulphide  in  mixtures  of  sodium  sul- 
phide and  sulphydrate,  clear  solutions  of  mercuric  sulphide  in  sodium  sul- 
phide and  sodium  hydrate  were  made,  all  of  the  reagents  being  carefully 


SOLUBLE  SULPHOSALTS  OP  MERCURY. 


425 


prepared  for  the  purpose,  and  sulphureted  hydrogen  was  passed  through 
the  solution  until  a  large  permanent  precipitate  of  mercuric  sulphide  had 
formed  The  mass  was  then  filtered,  and  of  course  the  filtrate  represented 
an  absolutely  saturated  solution  of  mercuric  sulphide  in  a  mixture  of  sodic 
sulphide  and  sulphydrate.  A  portion  of  this  solution  was  analyzed.  The 
remainder  was  treated  further  with  hydrogen  sulphide,  the  precipitation 
being  arrested  before  the  separation  of  mercuric  sulphide  was  complete,  and 
the  second  filtrate — representing  a  second  saturated  solution  of  the  metallic 
sulphide  in  a  mixture  of  alkaline  sulphide  and  sulphydrate,  but  one  contain- 
ing much  less  mercuric  sulphide  than  the  first  —  was  also  analyzed. 

Two  such  analyses  gave  the  following  results  per  100cm3  of  solution: 


A. 

B. 

Mercury,  Hg  

Grams. 
1.4417 

Grams. 
0  4976 

Sodium  Na  

4.  7990 

4  7790 

Sulphur  S 

5  9"W) 

6  4220 

It  will  readily  be  found  that  each  of  these  analyses  corresponds  closely 
to  the  formula  HgS,  4Na2S  +  «Na2S,  IPS.1 

The  degree  of  correspondence  can  best  be  seen  by  supposing  all  the 
errors  of  measuring,  weighing,  spontaneous  decomposition,  and  of  the  ana- 
lytical methods  employed  to  be  concentrated  in  the  determination  of  the 
sulphur.  Had  the  sulphur  found  been  5.9848  in  A  and  6.4102  in  B  the 
analyses  would  correspond  accurately  to  the  following  : 

(A)  HgS  +  4Na2S  +  10.473  Na2S,H2S. 

(B)  HgS  +  4Na2S  +  37.757  Na2S,  H2S. 


The  error  here  supposed  in  the  sulphur  determination  of  B  is  less  than 
one-fifth  of  1  per  cent,  of  the  entire  sulphur  found,  and,  considering  the 
quantities  actually  weighed,  it  comes  within  the  legitimate  inaccuracies  of 
analysis.  The  error  supposed  in  A  is  somewhat  less  than  1  per  cent,  of 
the  entire  sulphur,  and,  when  it  is  remembered  that  it  really  represents  the 

1  The  mercury  is  of  course  saturated  with  sulphur.  The  sodium  may  also  be  regarded  as  combined 
in  the  form  of  Na-S.  Deducting  the  corresponding  quantities  of  sulphur,  a  remainder  is  left,  which  is 
the  sulphur  combined  with  hydrogen  in  the  sulphydrate  Na2S,  H2S. 


426  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

sum   of  all  the  errors  of  experiment  and  analysis,1  the   variation  is  not 


great. 


In  another  analysis  of  this  solution,  devised  for  the  purpose  of  deter- 
mining separately  the  sulphur  combined  with  the  hydrogen  and  that  directly 
united  with  sodium  (an  attempt  which  was  only  approximately  successful), 
the  total  sulphur  also  actually  came  out  somewhat  higher  than  in  that  cited. 

These  analyses,  which  formed  the  conclusion  of  a  tedious  series  of 
experiments,  appear  to  me  to  show  beyond  any  reasonable  doubt  that 
there  is  a  compound  HgS,  4Na2S  which  is  soluble  in  the  presence  of  Na2S, 
IPS  and  which  is  decomposed  by  hydrogen  sulphide  in  the  presence  of 
sulphydrate  by  the  reaction  HgS,  4Na2S  +  4H2S  =  HgS  +  4Na2S,  H2S. 

conclusions  from  the  experiments. —  It  appears  from  the  above  that  there  are  at 
least  three  double  salts  of  the  form  HgS,  «Na2S  where  n  may  be  1,  2, 
or  4,  and,  judging  from  the  analogy  of  the  potassium  compounds,  there  is 
probably  also  a  compound  of  this  group  where  n  is  £.  The  possibility  of  a 
case  in  which  n  is  3  has  also  been  adverted  to.  Thus  mercuric  sulphide 
readily  enters  into  combination  with  sodic  sulphide  in  various  proportions, 
while  all  the  best  known  soluble  compounds  of  mercuric  sulphide  and  sodium 
have  the  same  general  formula,  The  presence  of  carbonates  of  the  alkalis 
is  also  known,  especially  from  Mehu's  results,  to  be  compatible  with  the  ex- 
istence of  these  compounds.  The  question  therefore  arises  whether  such 
double  sulphides  may  not  exist  in  natural  waters. 

Possible  existence  of  Na'S  in  natural  waters. This    question    I'CSOlveS    itself  HltO    tWO. 

It  is  to  be  considered  whether  sodic  sulphide  may  exist  in  natural  waters  as 
such.  In  that  case  such  waters  must  dissolve  mercuric  sulphide.  It  is  also 
possible  that  alkaline  monosulphides  cannot  exist  as  such  in  these  waters,  but 
that  the  affinity  of  the  compounds  Na2S  and  HgS  is  sufficient  to  overcome 
the  obstacles  to  the  formation  of  sodic  sulphide  and  that  this  compound  will 
form  when  mercuric  sulphide  is  present.  The  latter  possibility  is  the  more 
important,  but  the  former  is  manifestly  one  of  interest  to  chemical  geology. 
It  seems  commonly  to  be  assumed  that  only  the  acid  carbonate  of  sodium 
exists  in  natural  waters.  I  know  of  no  warrant  for  this  assumption.  The 

1  Among  other  sources  of  error  in  working  with  these  compounds  is  the  absorption  of  carbonic  acid 
and  the  liberation  of  H2S.    The  solutions  never  cease  to  smell  of  the  latter. 


ilTIBSXTY 


SODIUM  SULPHIDE  IN  NATUI%l^7ATBIfS^tV/       427 

^^WFOr.?)^ 
^ ^^^^ 

neutral  carbonate  and  the  sesquicarbonate  are  known  to  crystallize  from  many 
natural  waters.  It  is  even  difficult  to  produce  the  acid  carbonate  free  from 
the  neutral  salt,  and  the  acid  carbonate  of  commerce,  though  designed  to  be 
pure,  invariably  contains  a  considerable  amount  of  the  more  basic  compound. 
Hot  solutions  of  acid  carbonate  lose  carbonic  acid  rapidly  and  cold  solu- 
tions evaporating  in  dry  air  also  lose  a  large  part  of  their  acidity,  so  that 
the  neutral  carbonate  and  carbon  dioxide  may  coexist.  In  my  opinion  it  is 
only  safe  to  regard  natural  waters  as  in  general  containing  both  carbonates. 
When  hydrogen  sulphide  is  passed  through  waters  containing  neutral 
carbonate  at  ordinary  temperatures  the  following  reaction  is  known  to  take 
place:  Na2C03+H2S=NaIIC03+NaHS ;  so  that,  if  the  solution  of  the 
neutral  carbonate  be  moderately  strong,  a  portion  of  the  less  soluble  acid 
carbonate  is  precipitated  by  hydrogen  sulphide.  If  hydrogen  sulphide  be 
passed  through  the  solution  until  it  is  only  semi-saturated  or  if  a  saturated 
solution  be  added  to  a  solution  of  the  neutral  carbonate,  the  composition 
will  be  Na2C03+NaIIC03+NaHS. 

It  is  evidently  conceivable  that  the  neutral  carbonate  should  react 
upon  the  sulphydrate,  producing  sodium  sulphide  and  acid  carbonate. 
This  reaction  cannot  take  place  under  ordinary  conditions,  however,  for  the 
thermal  effect  of  Na2C03+NaHS  =  NaHC03+Na2S  is  negative.  It  does 
not  follow  that  this  reaction  may  not  take  place  at  temperatures  approach- 
ing 100°.  Indeed,  in  connection  with  the  known  facts  as  to  the  solubility 
and  hydration  of  sodium  carbonate  at  different  temperatures,  it  is  a  conse- 
quence of  a  somewhat  complex  train  of  reasoning  on  the  thermal  effects  of 
the  formation  of  the  compounds  involved  that  the  following  reaction  must 
give  a  positive  thermal  effect  when  the  temperature  exceeds  80°: 
2Na2CO 3  +  2NaIIC03  +  2NaHS  =  2NaHC03, 

Na2  CO3  +  NaHCO3  +  NaHS  +Na2S. 

If  this  reaction  actually  takes  place,  a  mixture  of  the  two  carbonates  with 
the  sulphydrate,  raised  to  a  temperature  of  above  80°,  yields  a  portion  of  the 
simple  sulphide  of  sodium.  This  appears  to  give  a  greater  thermal  effect 
than  any  other  reaction  which  can  be  devised  between  the  ingredients.  It 
does  not  of  necessity  follow  that  it  takes  place ;  for  the  salts  may  possibly 
present  unknown  resistances  to  combination  similar  to  the  resistance  which 


428  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

prevents  the  combination  of  free  hydrogen  and  oxygen  at  low  temperatures. 
There  is,  however,  nothing  to  indicate  such  anomalous  resistances,  and  in 
any  event  the  considerations  adduced  demonstrate  a  tendency  to  the  forma- 
tion of  sodium  sulphide.  On  the  other  hand,  though  many  efforts  have 
been  made,  neither  Dr.  Melville  nor  I  have  succeeded  in  devising  an  ex- 
perimental method  proving  the  presence  of  sodic  sulphide,  as  such,  in 
solutions  of  this  kind.  If  it  does  exist,  of  course  mercuric  sulphide  must 
immediately  dissolve  in  the  solution  without  the  evolution  of  gas. 

The  theoretical  results  given  in  the  last  paragraph  were  worked  out 
before  a  single  one  of  the  experiments  described  in  this  chapter  was  made, 
and,  in  fact,  formed  the  basis  of  the  entire  investigation.  When  the  attempt 
was  made  to  dissolve  mercuric  sulphide  in  the  mixture,  at  the  temperature 
indicated,  in  open  vessels,  it  was  found  to  go  into  solution  without  evolution 
of  gas,  thus  behaving  as  if  free  sodic  sulphide  were  present.  This,  however, 
in  view  of  the  facts  afterwards  ascertained,  does  not  prove  the  actual  pres- 
ence of  free  sodic  sulphide. 

Formation  of  Na*s  in  the  presence  of  Hgs. — When,  in  addition  to  the  tendency 
towards  formation  of  sodic  sulphide  discussed  above,  the  affinity  of  mercuric 
sulphide  for  this  compound  is  brought  into  play,  it  can  be  proved  experi- 
mentally that  sodic  sulphide  is  formed.  We  found  that  at  a  temperature  of 
about  90C  a  mixture  of  the  two  carbonates  and  the  sulphydrate  dissolves 
mercuric  sulphide  freely  without  a  sensible  evolution  of  gas.  If  the  solvent 
does  not  contain  sodic  sulphide,  it  must  contain  the  sulphydrate.  Hence  it 
becomes  important  to  ascertain  the  behavior  of  mercuric  sulphide  to  so- 
dium sulphydrate  at  moderately  elevated  temperatures. 

While  sodic  sulphydrate  will  not  dissolve  a  trace  of  mercuric  sulphide 
at  ordinary  temperatures,  if  mercuric  sulphide  be  added  to  a  solution  of  so- 
dium sulphydrate  which  stands  upon  the  water-bath,  hydrogen  sulphide  is 
evolved  and  mercuric  sulphide  goes  into  solution.  The  fact  that  hydrogen 
sulphide  is  evolved  demonstrates  that  sodic  protosulphide  must  be  formed. 
Cooling  does  not  reprecipitate  the  mercuric  sulphide,  and  the  compound  dis- 
solved is  therefore  of  the  form  HgS,  «Na2S.  Though  the  solubility  of  mer- 
curic sulphide  in  warm  solutions  of  the  alkaline  sulphydrates  at  ordinary 
pressures  has,  so  far  as  I  know,  never  been  explicitly  stated,  I  have  no 


FORMATION  OF  MERCURIC  SULPHO3ALT.  429 

doubt  that  chemists  have  observed  it,  and  that,  in  consequence  of  this  ob- 
servation, the  general  statement  of  the  solubility  of  mercuric  sulphide  in 
alkaline  stilphydrates  h;is  remained  in  chemical  literature  in  spite  of  the 
observations  of  Weber  and  Barfoed.  The  preparation  in  which  I  origi- 
nally observed  this  important  reaction  was  one  from  which  mercury  had 
already  been  removed  by  precipitation  with  hydrosulphuric  acid  The  ex- 
periment was  afterwards  repeated  by  Dr.  Melville  with  several  preparations 
of  sulphydrate  which  had  been  accurately  analyzed  and  had  been  tested 
in  numerous  ways. 

Now,  in  a  mixture  of  the  carbonates  and  sulphides  at  the  temperature 
of  the  water-bath,  .either  sodic  sulphide  or  sulphydrate  is  present,  or,  more 
probably,  they  coexist.  If,  then,  mercuric  sulphide  be  added  to  such  a  so- 
lution, either  sodic  .sulphide  combines  directly  with  mercuric  sulphide  or 
sodic  sulphydrate  is  decomposed  by  mercuric  sulphide,  setting  free  hydro- 
gen sulphide,  which  must  be  immediately  absorbed  by  sodium  monocar- 
bonate.  Hence,  in  any  case  the  salt  dissolved  in  the  solvent  must  be  of 
the  form  HgS,  «Na*S. 

Effects  of  dilution. —  Laboratory  experiments  are  usually  made  with  solutions 
which  are  more  concentrated  than  those  found  in  nature.  Hence  the  effect 
of  dilutions  on  solutions  of  HgS,  wNa2S  is  important.  Whether  mercuric 
sulphide  be  dissolved  in  a  mixture  of  sodium  protosulphide  and  sodium  hy- 
drate or  of  the  former  and  sulphydrate,  dilution  with  cold  water  precipi- 
tates mercuric  sulphide.  The  process  is  gradual,  yet  progresses  in  stages. 
Thus  a  mixture  of  solutions  of  sodic  sulphide  and  sodic  hydrate  of  a  vol- 
ume of'  3.9cm3  was  nearly  saturated  with  mercuric  sulphide.  The  mixt- 
ure was  represented  by  the  formula  HgS  +  2.04Na2S  +  1.38NaHO  +  aq 
and  contained  0.3349  gram  of  mercuric  sulphide.  Supposing  no  change 
of  volume  to  have  taken  place,  this  is  equivalent  to  80  grams  of  mercuric 
sulphide  per  liter.  On  dilution  no  precipitate  was  observable  until  25cm3 
of  water  had  been  added,  or  until  the  contents  were  reduced  to  11.6 
grams  of  mercuric  sulphide  per  liter.  Precipitation  appeared  to  continue 
until  about  100cm3  of  water  had  been  added.  There  then  remained  in 
solution  0.0753  gram  by  weight,  or  0.724  gram  per  liter.  The  filtrate 
remained  clear  until  enough  water  had  been  added  to  reduce  the  strength 


430  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

of  the  solution  to  0.29  gram  per  liter.  Then  the  liquid  began  to  grow 
darker  and  the  color  deepened,  until  the  entire  quantity  of  sulphide  pres- 
ent was  about  0.12  gram  per  liter.  The  precipitated  material  was  so  finely 
divided  that  it  would  not  settle  and  could  not  be  filtered  out,  and  it  was 
therefore  impossible  to  say  where,  if  at  all,  the  precipitating  effect  of  water 
ceases.  Similar  experiments  yielding  analogous  but  not  numerically  iden- 
tical results  were  made  with  other  solutions. 

The  cause  of  this  precipitation  is  clear.  It  is  known  through  the  in- 
vestigation of  Messrs.  Kolbe,  Thomson,  and  others  that,  while  in  moderately 
concentrated  solutions  NaHS  +  NaIlO=:Na"S  +  H2O,  this  reaction  is  par- 
tially reversed  on  dilution,  or  that  in  the  presence  of  much  water  sodic 
sulphide  is  decomposed  by  water,  the  proportion  of  the  sulphide  under- 
going this  decomposition  increasing  gradually  with  the  dilution.  It  is  evi- 
dent that  the  decomposition  of  HgS,  «Na2S  is  effected  in  the  same  way, 
more  and  more  of  the  protosulphide  in  combination  being  converted  into 
the  sulphydrate  as  the  dilution  increases,  probably  without  any  limit.  Since 
mercuric  sulphide  decomposes  hot  sodic  sulphydrate,  the  effect  of  dilution  in 
hot  solvents  will  evidently  be  less  than  in  cold  ones. 

Brunner  found  that  dilution  of  solutions  of  such  a  salt  precipitated  a 
black  mass,  in  which,  on  examination  with  the  lens,  minute  globules  of 
mercury  were  visible.  The  quantity  of  mercury  was  extremely  small,  so 
that  the  precipitate,  on  analysis,  corresponded  very  closely  indeed  to  the 
composition  expressed  by  the  formula  HgS.  Gmelin-Kraut1  appear  to 
have  some  independent  confirmatory  evidence  on  this  point.  If  metallic 
mercury  be  precipitated  in  diluted  solutions,  of  course  sulphur  is  liberated, 
and,  as  shown  above,  alkaline  hydrate  must  also  be  present.  Now,  when 
these  two  substances  are  brought  in  contact,  sodic  hyposulphite  forms 
Accordingly  Brunner  found  hyposulphite  in  solution  forty  years  before 
the  decomposition  of  alkaline  sulphide  in  dilute  solution  had  been  eluci- 
dated. 

As  Brunner  experimented  with  HgS,  K2S,  I  thought  it  best  to  com- 
pare the  action  of  HgS,  4Na2S.  A  very  concentrated,  perfectly  clear  solu- 
tion of  freshly  prepared  mercuric  sulphide  in  a  mixture  of  sodic  sulphy- 

1  ll.-milliiirli  iler  Clicmie,  vol.  :!,  i>.  •".">!. 


EFFECT  OF  FOREIGN  SUBSTANCES.  431 

drate  and  sodic  hydrate,  containing  very  little  of  the  latter,  was  suddenly 
diluted  with  cold  water  to  two  hundred  times  its  volume  and  rapidly  filtered. 
Minute  globules  of  mercury  could  be  seen  with  the  black  sulphide  on  the 
filter.  On  digestion  (after  thorough  washing)  with  very  dilute  nitric  acid, 
a  solution  was  obtained  from  which  sulphydric  acid  precipitated  black  sul- 
phide. The  decomposition  thus  appears  to  be  the  same  in  solutions  of  each 
of  the  compounds  HgS,  K2S  and  HgS,  4Na2S. 

influence  of  foreign  substances. — The  fact  that  sodium  carbonates  do  not  pre- 
vent the  solution  of  mercuric  sulphide  is  evident  both  from  Mehu's  result 
and  from  our  own.  As  was  mentioned  above,  mercuric  sulphide  dissolves 
abundantly  in  a  solution  containing  these  carbonates  and  sodic  sulphides. 
The  chief  constituents  of  the  waters  of  Steamboat  Springs  and  Sulphur 
Bank,  besides  alkaline  carbonates  and  sulphides,  are  borax  and  salt.  Ex- 
periments show  that  borax  solutions  precipitate  a  portion  of  the  mercury 
from  solution,  but  not  the  whole.  The  precipitation  does  not  appear  to  be 
progressive,  like  that  accompanying  dilution,  but  to  reach  a  sharp  limit 
beyond  which  further  additions  produce  no  effect.  A  large  amount  of  bo- 
rax added  to  a  concentrated  solution  "of  sodic  sulphide  and  sodic  sulphy- 
drate  does  not  rob  it  of  the  power  to  dissolve  mercuric  sulphide. 

It  is  easy  to  imagine  reactions  by  which  borax  may  precipitate  a  por- 
tion of  the  mercuric  sulphide.  It  seems  possible,  for  example,  that  neutral 
borate  is  formed  at  the  expense  of  the  sodic  sulphide  combined  with  the 
mercuric  sulphide.  The  sodic  sulphide  would  then  be  converted  to  sulphy- 
drate  and  mercuric  sulphide  would  precipitate.  But  the  behavior  of  solu- 
tions of  borax  to  sulphydric  acid  and  to  alkaline  sulphides  is  very  peculiar, 
and,  so  far  as  I  am  aware,  has  not  been  thoroughly  investigated.1  Very 
concentrated  solutions  of  sodium  chloride  do  not  precipitate  mercuric  sul- 
phide from  strong  solutions  in  mixtures  of  sodic  sulphide  and  sulphydrate, 
and  they  even  appear  to  delay,  but  not  to  prevent,  precipitation  by  dilution. 

The  waters  of  Steamboat  Springs  contain  no  ammonia  and  probably 
no  organic  matter.  Those  of  Sulphur  Bank  carry  ammonia,  and  all  of  the 
mines  examined  in  California  show  more  or  less  organic  matter.  It  is  highly 
probable,  therefore,  that  during  the  period  of  ore-deposition  more  or  less 

1  Gmelin-Kraut,  loc.  clt.,  vol.  2,  p.  160. 


432  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

ammonia  was  present  in  many  cases.  Very  small  quantities  of  ammonium 
carbonate  precipitate  all  the  mercury  from  the  solutions  discussed  above  at 
ordinary  pressures  and  at  temperatures  not  exceeding-  the  boiling-point.  At 
temperatures  of  145°  or  more  and  corresponding  pressures,  however,  mer- 
curic sulphide  dissolves  freely  in  ammoniacal  solutions,  but  it  is  repre- 
cipitated  on  cooling.  The  entire  absence  of  cinnabar  from  the  original 
surface  of  Sulphur  Bank  shows  how  complete  this  precipitation  must  be 
and  that  a  "quantitative"  separation  of  mercuric  sulphide  has  there  taken 
place  (see  page  269). 

solubility  of  PCS' — The  sulphide  which  is  most  frequently  associated  with 
cinnabar  is  pyrite  or  marcasite  ;  indeed,  these  minerals  in  greater  or  smaller 
quantities  are  to  be  found  in  nearly  every  hand  specimen  of  ore  and  occur 
very  abundantly  in  most  quicksilver  mines.  It  seems  impossible  to  avoid 
the  conclusion  that  the  iron  sulphides  are  soluble  in  the  same  natural  solu- 
tions which  carry  cinnabar.  Pyrite,  however,  is  a  mineral  which  is  so 
refractory  to  most  chemical  solvents  that  neither  Dr.  Melville  nor  I  felt  any 
confidence  that  sodium  sulphide  would  attack  it.  On  making  the-  experi- 
ment I  was  accordingly  surprised  to  find  that  pyrite,  marcasite,  or  precipi- 
tated ferrous  sulphide,  when  warmed  with  a  solution  of  sodic  sulphide, 
diminished  in  quantity,  while  the  solution  changed  color.  The  filtrates  gave 
strong  reactions  for  iron. 

Pyrite  dissolves  in  cold  solutions  of  sodium  sulphide  without  any  evo- 
lution of  gas.  Ten  cubic  centimeters  of  an  irreproachable  solution  of  sodic 
sulphide  containing  1.0955  grains  of  the  alkaline  sulphide  dissolved  six- 
tenths  of  a  milligram  of  pyrite  at  the  ordinary  temperature  of  the  laboratory. 
Thus  over  eighteen  hundred  parts  of  sodic  sulphide  are  required  to  dissolve 
one  part  of  pyrite.  The  solvent  power  seems  to  increase  with  the  tempera- 
ture. Pyrite,  like  cinnabar,  appears  to  be  totally  insoluble  in  cold  sodium 
sulphydrate,  and,  like  cinnabar,  pyrite  dissolves  to  some  extent  in  hot  solu- 
tions of  the  sulphydrate.  Pyrite  is  also  soluble  in  solutions  of  sodium  car- 
bonate partially  saturated  with  Irydrogftn  sulphide,  both  hot  and  cold.  A 
solution  of  407  parts  of  the  neutral  carbonate,  after  being  semi-saturated  with 
hydrogen  sulphide,  dissolved  one  part  of  pyrite  at  the  ordinary  temperature 
of  the  laboratory.  The  mineral  dissolves  morn  easily  in  hot  solutions  than  in 


SOLUBILITY  OF  GOLD.  433 

cold  ones.  Marcasite  is  more  easily  soluble  than  pyrite,  and  the  simple 
precipitated  sulphide  goes  into  solution  most  readily  of  all.  I  think  there 
can  be  no  doubt  that  pyrite  and  marcasite  form  double  salts  with  sodium 
sulphide  entirely  analogous  to  the  soluble  compounds  of  mercuric  sulphide. 
Marcasite  is  more  easily  attacked  than  pyrite,  just  as  metacinnabarite  is 
more  susceptible  to  the  action  of  reagents  than  is  cinnabar. 

soiuwiity  of  gold. — The  association  of  gold  and  pyrite  is  world-wide.  Ac- 
cording to  Gahn1  there  is  no  pyrite  which  does  not  yield  traces  of  gold 
when  carefully  tested.  This,  indeed,  does  not  accord  with  my  experience, 
for  extremely  careful  tests  of  some  pyrite  in  my  laboratory  have  failed  to 
reveal  any  indication  of  gold.  Gold  is  associated  with  quicksilver,  however, 
at  Steamboat  Springs,  at  some  points  on  the  gold  belt  of  California,  at  the 
Manzanita  mine,  at  the  Redington  mine,  and  some  other  localities.  From 
these  facts  I  concluded  that  gold  should  be  soluble  in  sodic  sulphide.  On 
warming  chemically  pure  precipitated  gold  dust  with  a  solution  of  sodic 
sulphide  the  glittering  scales  of  gold  gradually  disappeared.  The  filtrate 
after  a  proper  manipulation  yielded  a  purple  precipitate  with  phosphorous 
acid.2 

A  solution  containing  843  parts  of  sodic  sulphide  (Na2S)  by  weight 
dissolves  one  part  of  gold  at  the  ordinary  temperature  of  the  atmosphere. 
Gold  also  dissolves  in  sodic  sulphydrate  and  in  solutions  of  sodic  carbonate 
partially  saturated  with  sulphydric  acid  at  ordinary  temperatures.  The 
solubility  appears  to  be  increased  and  facilitated  by  heat. 

solubility  of  cus. — Cupric  sulphide  dissolves  less  readily  than  pyrite.  Ex- 
periments were  made  by  keeping  CuS  in  contact  with  the  solvents  in  bottles 
at  about  20°  C.  for  two  weeks,  the  bottles  being  shaken  from  time  to  time. 
A  little  less  than  five  thousand  parts  by  weight  of  sodic  sulphydrate  are 
required  to  dissolve  one  part  of  copper  sulphide.  About  eight  thousand 

'BischoPs  Cbeui.  uud  phys.  Gcol.,  vol.  3,  I860,  p.  939. 

•Bischof  long  since  remarked  that,  were  the  existence,  of  sulphide  of  gold  in  nature  proved,  the 
possibility  of  double  sulphides  of  this  metal;  such  as  can  be  artificially  produced,  and  of  their  deposi- 
tion from  aqueous  solutions  would  be  ascertained  (ibid.,  p.  838).  So,  also,  Prof.  T.  Kgleston  has  found 
that  gold  kept  in  contact  v.'ith  alkaline  sulphides  produced  solutions  giving  reactions  for  gold  (Trans. 
Am.  Inst.  Min.  Kug.,  vol.  9,  1831,  p.  (HO).  He  did  not  show,  however,  how  such  sulphides  or  tliei; 
iM|iiivalents  could  form  or  exist  in  nature,  ami  seems  to  conclude  that  the  compound  existing  in  natural 
solutions  is  the  chloride. 

MON   XIII 28 


434  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

parts  of  sodic  sulphide  in  the  presence  of  caustic  soda  are  required  to  pro- 
duce the  same  effect.  Cupric  sulphide  is  also  soluble  at  20°  in  the  solution 
of  sodium  carbonate  to  which  sulphydric  acid  has  been  added.  Over  two 
thousand  parts  of  neutral  sodium  carbonate  which  had  been  semi-saturated 
with  hydrogen  sulphide  were  required  to  dissolve  one  part  of  cupric  sul- 
phide at  this  temperature.  Cupric  sulphide  is  also  soluble  in  each  of  these 
solutions  when  hot. 

solubility  or  zns. — The  experiments  on  zinc  sulphide  were  made  in  the  same 
manner  as  on  cupric  sulphide.  Zinc  sulphide  is  more  soluble  in  a  mixture 
of  sodic  sulphide  and  caustic  soda  than  in  sodic  sulphydrate.  A  solu- 
tion containing  a  little  less  than  a  thousand  parts  of  Na2S  and  about  one 
hundred  parts  of  NaliO  dissolved  one  part  of  ZnS  at  20°.  The  sulphydrate 
dissolves  only  a  very  small  quantity  of  zinc  sulphide.  Sodic  carbonate  par- 
tially saturated  with  sulphydric  acid  also  dissolves  zinc  sulphide.  Over  one 
thousand  parts  of  neutral  sodium  carbonate  which  had  been  semi-saturated 
with  hydrogen  sulphide  were  found  necessary  to  dissolve  one  part  of  zinc 
sulphide  at  20°. 

soiuwuty  oi  AS'S'  and  sb's'. —  It  is,  of  course,  perfectly  well  known  that  the 
sulphides  of  arsenic  and  antimony  dissolve  freely  in  sodic  sulphide  without 
evolution  of  gas  and  in  sodic  sulphydrate  with  the  evolution  of  hydrogen 
sulphide.  In  cold  solutions  of  sodic  carbonate  partially  saturated  with 
sulphydric  acid  they  dissolve  freely  without  liberation  of  gas,  because  the 
hydrosulphuric  acid  set  free  immediately  combines  with  sodic  carbonate. 

insolubility  of  pbs  and  Ag^s. — The  sulphides  of  lead  and  silver  seem  to  be  en- 
tirely insoluble  in  solutions  of  sodic  sulphide,  of  sodic  sulphydrate,  or  in 
solutions  of  sodic  carbonate  partially  saturated  with  hydrosulphuric  acid. 
We  have  obtained  no  evidence  of  solution  with  these  sulphides  even  when 
heated  above  100°  with  the  reagents  in  closed  tubes.  Galena  is  rarely 
found  in  quicksilver  mines  and  distinct  silver  minerals  are  still  more  seldom 
found  associated  with  cinnabar.  Very  little  galena  occurs  in  the  gold  mines 
of  California,  and  lead  deposits  usually  differ  widely  in  character  and  mode 
of  occurrence  from  either  quicksilver  or  gold  deposits.  These  facts  seem  to 
indicate  that  the  best  natural  solvent  for  lead  is  different  from  that  which  is 
most  effectual  in  dissolving  cinnabar  and  gold.  Mr.  de  Senarmont1  produced 


e> 

di-  cliiinic,  I'uris,  vol.  '.ti,  18.">l,]>]>.  ITi"1,  171. 


PRECIPITATION  IN  NATUEE.  435 

galena  by  the  solvent  action  of  water  supersaturated  with  sulphydric  acid 
in  closed  tubes  at  high  temperatures  and  pressures,  and  also  obtained  ruby 
silver,  both  arsenical  and  antimonial,  by  heating  alkaline  sulpharsenites  with 
silver  salts  dissolved  in  solutions  of  acid  sodic  carbonate  at  temperatures  of 
from  250°  to  350°.  There  is,  therefore,  nothing  strange  in  the  fact  that  lead 
and  silver  accompany  the  other  minerals  at  Steamboat  Springs. 

Natural  solutions  and  precipitations. — The  foregoing  analyses  and  experiments 
show  that  there  is  a  series  of  compounds  of  mercury  of  the  form  HgS,  wNa2S, 
one  or  the  other  of  which  is  soluble  in  aqueous  solutions  of  caustic  soda, 
sodic  sulphydrate,  or  sodic  sulphide,  and  apparently  also  in  pure  water  at 
various  temperatures.  These  solutions  subsist,  or  subsist  to  some  extent, 
in  the  presence  of  sodic  carbonates,  borates,  and  chlorides.  There  is  the 
strongest  evidence  that  the  waters  of  Steamboat  Springs  contain  mercury 
in  this  form  and  that  the  waters  of  Sulphur  Bank  still  carry  it  in  solution. 
Sulphides  of  iron,  gold,  and  zinc  form  double  sulphides  with  sodium,  which 
appear  to  be  entirely  analogous  to  those  of  mercury.  Copper  also  forms  a 
soluble  double  sulphide,  but  combines  more  readily  with  sodic  sulphydrate 
than  with  the  simple  sulphide.  All  of  these  soluble  sulphosalts  may  exist 
in  the  presence  of  sodic  carbonates. 

Mercuric  sulphide  is  readily  precipitated  from  these  solutions.  Any 
substance  is  more  soluble  in  hot  solutions  than  in  cold  ones,  provided  that 
increase  of  temperature  does  not  resolve  the  fluid  molecules  into  others 
which  are  less  soluble,  as  happens  with  sodium  chloride,  neutral  sodium  car- 
bonate, etc.  Diminishing  temperature  is  thus  a  cause  of  precipitation,  and 
diminishing  pressure  appears  to  act  in  a  similar  way.  At  Sulphur  Bank 
cinnabar  is  precipitated  at  a  short  distance  from  the  surface,  partly  at  least 
in  consequence  of  the  action  of  ammonium  salts.  There  are  also  other 
methods  of  precipitation  which  may  be  carried  out  under  natural  conditions. 
If  a  natural  solution  of  mercury  comes  in  contact  with  a  strong  solution  of 
borax,  or  with  sulphydric  acid  or  any  stronger  acid,  it  will  lose  a  portion 
of  the  more  uric  sulphide  in  solution,  and,  if  the  precipitation  be  a  rapid  one, 
the  black  sulphide  will  probably  be  thrown  down.  At  Steamboat  Springs 
and  Sulphur  Bank  large  quantities  of  sulphuric  acid  are  found  near  the  sur- 
face and,  percolating  downward,  must  precipitate  mercury.  The  acid  waters 


436  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

penetrate  to  a  depth  of  at  least  twenty  or  thirty  feet,  and  this  helps  to  ex- 
plain the  fact  that  the  water  reaching  the  surface  carries  so  little  quick- 
silver. These  same  causes,  or  some  of  them,  must  also  induce  precipitation 
of  the  other  ores  and  of  gold  from  solutions. 

Another  method  by  which  mercuric  sulphide  may  be  precipitated  is,  as 
has  been  seen,  mere  dilution.  Now,  ascending  solutions  of  quicksilver  must 
sometimes  meet  with  springs,  and,  when  they  do  so,  metacinnabarite  or 
black  sulphide  will  be  precipitated,  and  with  it  also  a  small  amount  of  me- 
tallic quicksilver.  In  nearly  all  mines  a  small  quantity  of  virgin  quick- 
silver is  found,  and  in  most  it  constitutes  a  very  small  proportion  of  the 
entire  ore.1  Accompanying  this  precipitation  is  the  formation  of  sodic  hypo- 
sulphite, which  actually  occurs  in  the  waters  of  Steamboat  Springs.  Dilu- 
tion of  solutions,  of  quicksilver  with  extraneous  spring  waters  thus  affords 
one  method  of  explaining  the  occurrence  of  metacinnabarite2  found  in  at 
least  five  of  the  mines  of  California,  and  also  that  of  native  quicksilver. 
Native  quicksilver,  however,  occurs  in  many  mines  in  which  no  metacin- 
nabarite has  ever  been  seen.  This  does  not  preclude  the  supposition  that 
the  metal  has  been  isolated  by  dilution,  for  black  sulphide  in  the  presence  of 
solutions  of  mercury  might  readily  be  converted  into  the  allotropic  modi- 
fication, and  I  know  of  no  reason  for  denying  that  much  of  the  cinnabar  of 
the  ore  deposits  may  have  been  deposited  in  the  amorphous  state.  Cinna- 
bar and  metacinnabarite  are  sometimes  found  mixed,  as  if  a  conversion  to 
the  red  mineral  were  incomplete.  In  one  of  the  abandoned  drifts  near  the 
exhausted  ore  bodies  of  the  New  Idria  mine  the  walls  were  covered  with 
incrustations  of  secondary-  salts  over  an  inch  in  thickness.  In  this  mass, 

*/ 

which  had  been  deposited  since  the  drift  was  opened,  I  found  a  tiny  vein  of 
cinnabar,  about  three  inches  in  length  and  perhaps  a  quarter  of  a  milli- 
meter in  thickness.  The  existence  of  this  very  recently  formed  veinlet  evi- 
dently indicates  the  presence  in  the  mine  of  solvents  of  mercuric  sulphide 
in  trifling  quantities,  which  might  be  quite  sufficient,  however,  to  convert 
black  ore  into  cinnabar.  Professor  Sandberger  has  described  a  series  of 

1  It  is  a  very  curious  fact  that  from  ancient  times  to  tbe  beginning  of  the  last  century  virgin  quick- 
silver was  supposed  to  possess  qualities  superior  to  that  of  the  metal  reduced  from  cinnabar  (Briick- 
mann,  Magualia  Dei  in  Lm-is  Subterraneis). 

-'The  formation  of  metuciunaUarite  by  dilution  has  already  been  suggested  by  Mr.  S.  H.  Christy. 


DEPOSITION  OP  CINNABAR.  437 

specimens  from  Huitzuco,  in  Mexico,  which  also  seem  to  indicate  a  transfor- 
mation of  metacinnabarite  into  the  red  sulphide  by  the  action  of  solvent 
fluids  (see  page  19).  The  mercury  found  at  the  Great  Geyser  of  Iceland  is 
also  surrounded  by  black  sulphide,  which  at  a  greater  distance  from  the 
metallic  globules  passes  over  into  the  red  modification. 

While  dilution  will  produce  metallic  mercury  and  a  causa  vera  of  its 
existence  is  thus  detected,  there  may  be  other  ways  besides  this  in  which 
it  is  produced  in  nature.  Thus  sulphydric  acid  precipitates  a  mixture  of 
quicksilver  and  mercuric  sulphide  from  mercurous  salts.  Whether  soluble 
mercurous  salts  can  occur  in  nature,  excepting  near  the  earth's  surface,  is 
another  question.  But  even  light  is  well  known  to  decompose  this  feeble 
sulphide,  and  it  is  not  impossible  that  the  decomposition  of  organic  matter 
associated  in  most  cises  with  cinnabar  deposits,  and  which  seems  to  be 
especially  abundant  in  those  mines  in  which  metallic  mercury  most  prevails, 
may  lead  to  the  isolation  of  metallic  mercury. 

conclusions. — The  conditions  of  the  solution  and  precipitation  of  ores 
traced  in  this  chapter  appear  beyond  doubt  those  mainly  instrumental  in. 
forming  the  deposits  of  Steamboat  Springs  and  Sulphur  Bank.  Most  of  the 
other  quicksilver  mines  in  California  show  ores  and  gangue  minerals  of 
similar  composition  to  these,  and  many  of  them  are  accompanied  more  or 
less  closely  by  warm  springs  containing  much  the  same  salts  in  solution. 
Some  of  the  gold  veins  also  appear  to  bear  so  considerable  a  resemblance 
in  many  particulars  to  these  deposits  as  to  lead  to  the  belief  that  they  too 
were  formed  by  precipitation  from  solutions  of  soluble  double  sulphides. 

That  pyrite,  gold,  and  other  ores  are  sometimes  produced  in  nature  by 
other  methods  is  absolutely  certain,  for  some  auriferous  pyrite  is  known  to 
have  resulted  from  the  reduction  of  iron  sulphate  by  organic  matter.  This 
particular  process  is  probably  confined  to  short  distances  from  the  surface, 
for  I  know  of  no  indication  of  the  formation  of  iron  sulphate  far  from  the 
oxidizing  influence  of  the  atmosphere.  But  there  may  be  other  solvents 
yet  for  these  and  other  minerals  which  can  form  at  great  depths,  and,  if 
such  there  be,  I  am  convinced  that  there  are  cases  in  which  these  solvents, 
and  not  those  which  it  has  been  my  good  fortune  to  trace  in  the  foregoing 
pages,  have  been  instrumental  in  the  segregation  of  ores. 


CHAPTER  XVI. 

ORIGIN  OF  THE  ORE. 

Solvents  possibly  due  to  reduction  by  carbon. I  luiV6  sllOWll  that  Cinnabar  and  801116 

of  the  accompanying  minerals  are  dissolved  as  sulpliosalts.  It  is  now  desir- 
able to  consider  how  the  alkaline  sulphides  essential  to  these  solutions  are 
formed.  The  alkalis  found  in  thermal  springs  are  easily  explained,  inasmuch 
as  feldspathic  rocks  afford  an  inexhaustible  supply  of  sodium  and  potassium. 
The  source  to  which  sulphur  must  be  attributed  is  less  clear.  Many  geo- 
logical chemists,  among  them  Bischof,  maintain  that  sulphides  and  free 
sulphur  are  ultimately  referable  to  the  reduction  of  soluble  sulphides  by 
organic  matter.  That  sulphides  and  sulphur  are  frequently  produced  in 
this  way  is  entirely  beyond  question,  for  the  reduction  has  been  effected 
experimentally  and  has  been  observed  many  times  under  natural  and  arti- 
ficial conditions.  Gypsum,  for  example,  in  contact  with  water  and  carbon, 
yields  hydrogen  sulphide  and  acid  calcium  carbonate,  or  calcite  and  car- 
bonic anhydride.  If  salts  also  be  present  which  may  be  decomposed  by 
sulphydric  acid,  sulphides  will  be  formed. 

Soluble  sulphates  exist  in  the  greatest  abundance  in  nature,  being 
found  in  nearly  all  spring  water  and  forming  some  of  the  principal  constitu- 
ents of  sea  water.  There  can  also  be  no  doubt  that  a  very  large  part,  if 
not  the  whole,  of  the  water  flowing  from  thermal  springs  and  ejected  by 
volcanoes  is  of  superficial  origin  and  must  have  carried  soluble  sulphates 
with  it  to  the  depths  at  which  its  temperature  was  raised  to  a  maximum. 
Organic  matter  is  also  held  in  solution  or  mechanical  suspension  in  many 

438 


SODIUM.  439 

waters.  Besides  direct  observations  on  this  point,  it  is  a  well  known  fact 
that  below  the  permanent  water-level  of  a  country  reducing  agencies  are  at 
work,  so  that  the  heavy  metals  occur  as  sulphides  and  the  clays  are  com- 
monly tinted  blue  from  the  presence  of  ferrous  compounds.  Of  course  sedi- 
mentary rocks  of  all  ages  also  retain  carbon,  sometimes  in  large  quantities, 
as  graphite,  coal,  petroleum,  etc ,  so  that  reducing  matter  is  provided  at  all 
depths  to  which  sedimentary  strata  extend.  Organic  matter  is  also  said  to 
be  present  in  hot  springs  issuing  from  granite.  In  some  cases  granite  un- 
doubtedly overlies  sedimentary  rocks  and  some  granites  are  beyond  ques- 
tion metamorphic.  It  appears  to  me  possible,  however,  that  some  hot 
springs  issuing  from  granite  and  seeming  to  carry  organic  matter  do  not 
really  bring  such  compounds  to  the  surface ;  for  at  Steamboat  Springs,  in 
spite  of  the  very  high  temperature  of  the  water,  living  organisms  of  low 
forms  are  abundant  and  grow  luxuriantly  close  to  the  vents.  A  description 
of  the  circumstances  has  been  given  in  the  chapter  on  that  locality. 

Solvents  probably  independent  of  carbon SittCC      silicates     of     tll6      alkalis      and     tll6 

earths  are  decomposed  by  carbonic  acid  and  by  hydrogen  sulphide,  the  hy- 
pothesis that  these  reagents  are  due  to  the  interaction  of  soluble  sulphates 
and  organic  matter,  more  or  less  metamorphosed,  affords  a  method  of  ac- 
counting for  the  existence  of  solvents  for  the  ores.  It  is  by  no  means  cer- 
tain, however,  that  the  conditions  are  thus  adequately  explained.  In  his 
great  memoir  on  the  Icelandic  geysers,  Bunsen1  called  attention  to  the  fact 
that  in  gases  evolved  by  the  help  of  organic  matter,  either  in  nature  or  by 
artificial  processes,  hydrocarbons  are  almost  invariably  present.  In  a  very 
large  part  of  the  volcanic  emanations,  both  gaseous  and  fluid,  on  the  other 
hand,  hydrocarbons  are  wholly  wanting.  Hence  he  concludes  that  in  these 
cases  the  sulphur  and  hydrogen  sulphide  are  in  no  way  dependent  upon 
organic  matter.  Prof.  II.  Credner2  believes  that  most  of  the  gases  emanat- 
ing from  volcanoes,  including  sulphurous  acid  and  hydrogen  sulphide,  are 
disengaged  from  the  fluid  interior  of  the  earth  in  which  they  have  existed 
since  the  original  formation  of  the  globe.  Professors  Tschermak3  and 
E.  Reyer4  hold  similar  views.  From  the  point  of  view  of  the  nebular  hy- 

1  Poggendorff,  Annalen,  vol.  83.  3  Neues  Jahrbuch  fur  Mineral.,  1377,  p.  857. 

2  Elemente  der  Oeol.,  1887,  p.  170.  *  Fysik  der  Ernptioncn,  1887. 


440  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

pothesis  it  is  certainly  difficult  to  conceive  that  all  the  sulphur  compounds 
should  be  confined  to  the  surface  of  the  earth  or  that  all  the  sulphur  com- 
pounds not  occurring  near  the  surface  should  be  oxidized. 

Borax  is  another  component  of  the  spring  waters  which  it  is  difficult 
to  account  for,  except  on  the  hypothesis  that  the  waters  derive  a  portion 
of  their  mineral  constituents  from  beneath  the  granite.  Ordinary  surface 
waters  seldom,  if  ever,  contain  more  than  a  mere  trace  of  borax,  so  that  it 
is  highly  improbable  that  currents  descending  toward  the  source  of  heat 
carry  a  large  percentage  of  borax  with  them.  The  only  boron  mineral 
which  is  anywhere  abundant  in  granite  is  tourmaline,  but  this  mineral  is  so 
rare  in  the  granites  described  in  this  memoir  that  not  a  single  grain  of  it  has 
been  detected  in  the  slides.  It  is  somewhat  improbable,  therefore,  that  the 
waters  ascending  through  the  granite  have  derived  the  large  quantities  of 
borax  which  they  contain  from  that  rock.  This  improbability  is  strength- 
ened by  the  well  known  fact  that  boric  acid  accompanies  the  direct  sul- 
phurous emanations  of  many  volcanic  vents  It  is  indeed  conceivable  that 
the  borax  should  be  derived  from  sedimentary  rocks,  but  on  the  one  hand 
there  is  no  reason  to  suppose  that  the  granite  of  Steamboat  Springs  overlies 
any  sediments  and  on  the  other  hand  it  seems  doubtful  whether  strata  ever 
contain  any  considerable  quantity  of  borax  except  where  they  have  derived 
it  from  volcanic  emanations  in  the  neighborhood.  It  is  usual,  and  appears 
rational,  therefore,  to  ascribe  the  borax  of  hot  springs  to  a  volcanic  source 
the  character  of  which  is  unknown.  The  waters  of  Steamboat  Springs  and 
Sulphur  Bank,  it  will  be  remembered,  contain  relatively  large  quantities  of 
borax,  which  is  also  present  in  the  Knoxville  mineral  springs. 

Depths  at  which  solvents  are  found — Whether  the  hydrogen  sulphide  of  those 
thermal  springs  which  are  associated  with  other  volcanic  phenomena  is  due 
to  the  reduction  of  soluble  sulphates  by  organic  matter  by  some  unknown 
process  not  involving  the  production  of  hydrocarbons,  or  whether  it  is  due 
to  purely  inorganic  reactions  not  yet  elucidated,  as  seems  to  me  more  prob- 
able, it  is  evident  tint  this  gas  reaches  the  surface  from  considerable  depths, 
at  which  the  waters  percolating  from  the  surface  meet  with  rocks  of  greatly 
elevated  temperature.  In  cases  like  those  of  Steamboat  Springs  and  Sul- 


POSITION  OF  THE  SOURCE  OF  HEAT.  441 

phur  Bank,  where  the  associated  volcanic  phenomena  are  of  considerable 
age,  probably  thousands  of  years,  the  depths  at  which  these  heated  rocks 
lie  must  be  great.  It  is  true  that  a  body  of  lava  covered  with  dry  rock  of 
a  verv  moderate  thickness  would  remain  hot  for  a  very  long  time;  but,  at 
the  localities  mentioned  above,  constant  and  copious  streams  of  cold  water 
from  the  surface  are  heated  and  returned  to  the  surface.  In  both  localities, 
also,  this  very  effectual  cooling  process  has  been  in  operation  for  ages,  and 
probably  from  the  era  of  the  latest  volcanic  outbursts.  The  rocks  hot 
enough  to  heat  rapid  water  currents  to  such  an  extent  that  they  reach  the 
surface  with  a  temperature  of  nearly  or  quite  100°  must  therefore  lie  at 
great  depths.  On  the  Comstock  lode  the  heat  increment  is  1  °  F.  for  every 
33  feet.  If  the  same  increment  obtain  for  Steamboat  Springs  and  if  the 
rock  mass  which  heats  its  waters  be  at  a  very  low  red  heat  (about  500°  C.), 
the  depth  of  the  mass  below  the  surface  is,  in  round  numbers,  five  miles. 
The  Sierra  Nevada  has  been  a  land  area  from  the  Carboniferous  onwards, 
and  during  a  great  portion  of  this  immense  interval  it  has  been  a  mountain 
range  undergoing  rapid  erosion.  Its  granitic  surface  must  for  the  most 
part  be  extremely  ancient,  and  at  a  depth  of  five  miles  from  the  surface  it 
is  very  questionable  whether  there  can  be  any  rock  which  has  ever  been 
exposed  to  daylight.1  The  waters  rising  from  a  depth  of  five  miles,  and 
very  possibly  more,  pass  through  granite  which  bears  no  evidence  of  meta- 
morphic  origin,  and  possibly  through  other  rocks. 

Relations  of  the  deposits  to  various  rocks. — Granite  is  the  deep-seated  rock  beneath 
all  the  ore  deposits  mentioned  in  this  volume.  This  has  been  alluded  to  in 
former  chapters,  in  which  it  was  shown  that  granite  underlies  the  entire  Coast 
Ranges  and  supplied  the  material  of  which  the  sedimentary  rocks  of  that 
region  are  composed.  The  ore  deposits  themselves  are  found  in  various 
rocks :  At  Steamboat  Springs,  in  granite  and  to  a  small  extent  in  basalt ; 
at  Sulphur  Bank,  in  basalt,  in  Neocomian  sandstone,  and  in  recent  lake 
deposits ;  at  Mt.  Konocti,  in  andesite ;  at  Knoxville  and  New  Almaden,  in 
metamorphosed  Neooomian  strata ;  at  Oathill  and  to  a  slight  extent  in  Knox- 
ville, in  unmetamorphosed  Neocomian  strata;  at  New  Idria,  in  the  meta- 

1  Compare  "Origin  of  thci  massive  rocks,"  Chapter  IV,  p.  164. 


442  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

morphic  series  and  in  the  Chico ;  and  in  San  Luis  Obispo  County,  appar- 
ently in  Miocene  sandstones. 

Possible  sources  Of  the  ores. — In  tile  two  cases  just  mentioned,  in  which  cinnabar 
has  been  found  in  basalt,  this  lava  forms  a  thin  sheet  covering  earlier  rocks, 
and  in  each  case  the  ore  is  found  below  as  well  as  in  the  basalt.  The  ore 
certainly  is  not  derived  from  basalt.  Leaving  the  interesting  but  very  small 
deposits  in  andesite  out  of  the  question,  it  appears  that  all  the  other  deposits 
must  have  been  derived  from  granite,  or  from  rocks  composed  of  granitic 
detritus,  or  from  some  source  below  the  granite.  This  is  manifestly  equiv- 
alent to  the  statement  that  quicksilver  prior  to  its  solution  must  either  have 
formed  a  constituent  of  the  granite  or  must  have  dissolved  below  the  granite 
and  have  traversed  the  entire  thickness  of  that  rock  without  being  pre- 
cipitated. 

Observation  affords  no  clew  to  the  material  which  underlies  the  granites 
of  California.  Professor  Whitney  is  of  the  opinion  that  a  portion  of  these 
granites  is  comparatively  modern  and  I  am  by  no  means  prepared  to  con- 
trovert this  assertion,  but  it  is  certain  that  long  before  the  Post-Neocomian 
upheaval  granite  formed  the  bed  rock  of  a  great  part  of  that  State  and  of 
western  Nevada,  as  it  still  does.  The  fact  that  neither  in  California  nor  else- 
where do  we  know  anything  from  observation  of  what  underlies  the  granite 
on  which  the  older  strata  rest  shows  that  the  massive  rock  is  of  enormous 
thickness,  if  indeed  granite  and  granitoid  rocks  did  not,  as  elder  geologists 
supposed  and  as  is  maintained  in  Chapter  IV,  form  the  original  crust  of  the 
earth.  Before  undertaking  to  consider  whether  it  is  more  probable  that  the 
cinnabar  and  accompanying  minerals  were  derived  from  the  granite  or  that 
they  came  from  a  source  inferior  to  it,  it  seems  desirable  to  allude  briefly 
to  the  general  theories  held  by  geologists  with  regard  to  the  origin  of  ore 
deposits. 

Brief  statement  of  the  theories  of  the  genesis  of  ore  deposits. Five    distinct    tlieOl'IeS    liaVC 

been  maintained  in  geological  memoirs  respecting  the  methods  by  which 
the  ores  occurring  in  an  unstratified  condition  (as  veins,  stocks,  and  the 
like)  reached  the  positions  in  which  they  are  found.  These  are  known  as 
the  theories  of  simultaneous  formation,  descension,  injection,  ascension, 
and  lateral  secretion.  The  first  two  have  been  abandoned  for  many  years, 


THEORIES  OF  ORE  GENESIS.  443 

and  the  theory  of  injection,  so  far  as  ores  are  concerned,  is  limited  to  some 
very  subordinate  phenomena.  Those  remaining  are  variously  subdivided 
as  occasion  may  require.  With  appropriate  modifications  there  is  every 
reason  to  suppose  that  they  include  all  important  probable  cases.  It  does 
not  follow  that  they  present  the  subject  in  the  most  advantageous  manner. 
The  least  satisfactory  form  of  the  ascension  theory  asserts  that  the  origin 
of  the  ores  lies  below  the  deposits  in  some  unknown  position  from  which 
translocation  has  been  effected  by  unknown  means.  Lack  of  facilities  for 
investigation  may  in  some  cases  justify  no  more  definite  conclusion.  In 
other  instances  the  nature  of  the  occurrence  may  point  to  the  conclusion 
that  the  ores,  though  of  unknown  origin,  have  been  deposited  from  solution 
or  by  distillation.  The  ascension  theory  also  includes  case's  in  which  there 
is  evidence,  more  or  less  satisfactory,  as  to  the  source  whence  the  ore  was 
derived.  This  may  be  the  interior  of  the  earth,  as  is  maintained  by  many 
geologists,  for  some  veins  found  in  close  connection  with  active  volcanic 
phenomena,  or  the  origin  may  be  sought  In  deep-seated  rocks,  stratified  or 
massive,  but  similar  to  those  which  are  found  at  the  surface.  In  either 
case  there  may  or  may  not  be  sufficient  evidenca  to  justify  conclusions  as 
to  whether  the  ores  during  their  ascent  were  gaseous  or  in  solution. 

The  lateral  secretion  theory,  as  usually  defined,  is  that  ores  are  segre- 
gated from  rocks  contiguous  with  the  deposit.  The  statement  that  the  lat- 
eral secretion  theory  is  applicable  to  a  certain  case  does  not  convey  any 
implication  as  to  the  particular  side  from  which  the  ore  is  derived.  All  ore 
deposits  are  finite  and  any  finite  space  may  be  filled  from  any  one  of  six 
directions.  Neither  does  the  lateral  secretion  theory,  as  such,  involve  any 
conclusion  as  to  the  temperature  of  the  solutions  from  which  the  ore  has 
been  deposited.  It  is  even  possible  that  certain  valuable  minerals  have 
been  laterally  secreted  by  means  of  distillation,  though  this  is  no  doubt  an 
exceptional  and  limited  possibility. 

The  modifications  ot  these  two  theories  are  best  grasped  in  a  tabular 
form. 


444  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Ore  deposits  are  formed  — 
By  ascension  — 

(1)  From  unknown  sources: 

(a)  By  unknown  methods; 

(1}  By  deposition  from  hot  solutions; 

(c)  By  distillation,  with  or  without  steam. 

(2)  From  known  sources: 

(a)  From  the  original  interior  of  the  earth:  (a),  (i), 

and  (r),  as  above; 

(/?)  From  underlying  rocks:  («),  (?/),  and  (r),  as  above. 
By  lateral  secretion  (from  contiguous  rocks  on  any  side)  — 

(1)  Due  to  heated  waters  rising  from  below,  charged  with 

reagents; 

(2)  Due  to  cold  surface  waters,  which  become  charged  with 

reagents  in  permeating  the  rocks; 

(3)  Due  to  distillation  (a  rare  and  unimportant  case). 

It  will  be  observed  that  the  difference  between  the  lateral  secretion 
theory  and  the  ascension  theory  depends  simply  on  contiguity,  so  that,  as 
von  Cotta  pointed  out,  the  ascension  theory,  as  applied  to  rocks  contiguous 
to  an  ore  deposit,  becomes  a  case  of  the  lateral  secretion  theory.  For  the 
present  purposes  of  economic  geology  the  nomenclature  of  the  theories  is 
not  well  chosen.  Many  investigators  are  at  present  anxious  to  trace  those 
cases  in  which  ores  are  derived  from  rocks  accessible  from  the  surface,  and 
the  main  question  with  mining  geologists  is  now  whether  or  not  it  is  possi- 
ble to  prove  the  derivation  of  given  ores  from  rocks  existing  in  the  neigh- 
borhood of  the  deposit,  and,  if  so,  how  the  solution  and  deposition  have 
been  effected.  It  is  a  matter  of  detail  whether  the  ore  deposit  is  actually  in 
contact  with  the  rock  from  which  it  has  been  derived  or  is  separated  from 
it  by  masses  of  rock  which  exert  no  sensible  effect  upon  the  solutions. 

It  is  very  easy  to  regroup  the  special  forms  of  the  lateral  secretion  and 
ascension  theories  with  reference  to  this  point,  and  the  subject  seems  to  gain 
considerably  in  simplicity  by  this  step,  as  shown  in  the  following  state- 
ment: 


THEORIES  OF  ORE  GENESIS.  445 

Ores  are  derived — 

From  unknown  subterranean  sources: 

(1)  By  unknown  means; 

(2)  By  distillation ; 

(3)  By  solution,  hot  or  cold,  and  reprecipitation. 
From  rocks  such  as  occur  on  the  earth's  surface: 

(1)  By  unknown  means,  (a)  source  contiguous,  (6)  source 

remote ; 

(2)  By  distillation,  («)  source  contiguous,  (&)  source  remote; 

(3)  By  hot  solutions,  (a)  source  contiguous,  (6)  source  remote; 

(4)  By  cold  solutions,  («)  source  contiguous,  (6)  source  remote. 
From  the  earth's  interior: 

(1)  By  unknown  means; 

(2)  By  distillation; 

(3)  By  hot  solutions. 

Objections   to   an    infragranitic   origin As     liaS     bcCll     abundantly     pl'OVed     abOV6, 

either  the  quicksilver  deposits  of  the  Pacific  Slope  are  derived  by  means 
of  hot  solutions  from  the  granite,  which  is  contiguous  to  the  deposit  in  the 
case  of  Steamboat  Springs,  but  more  or  less  remote  in  all  other  instances, 
or  else  they  are  derived  as  heated  solutions  from  the  earth's  interior  (the 
region  below  the  granite).  Of  this  region  we  know  but  little.  It  sends  to 
the  surface  eruptive  rocks  and  volcanic  emanations,  gaseous  or  in  solution. 
These  emanations  almost  invariably  escape  in  large  quantities  from  the 
same  vents  from  which  the  lavas  flow,  but  also  often  escape  through  fissures 
at  considerable  distances  from  craters.  Eruptive  rocks  sometimes  contain 
gold,  silver,  lead,  and  other  metals,  and  it  cannot  be  asserted  that  they  may 
not  also  carry  quicksilver.  But,  were  the  source  of  quicksilver  nearly  or 
quite  identical  with  the  source  of  the" lavas,  one  would  expect  to  find  more 
or  less  quicksilver  within  the  craters  of  the  volcanic  vents,  from  which  sul- 
phurous, boracic,  and  alkaline  emanations  must  have  issued.  This  is  not 
the  case.  At  Sulphur  Bank  are  three  unmistakable  craters,  none  of  them 
showing  any  trace  of  cinnabar,  and  there  are  very  numerous  eruptive 
masses  throughout  the  quicksilver  belt  unassociated  with  quicksilver.  So- 
lutions of  the  heavy  metals  are  also  extremely  unstable,  their  sulphides 

(UKIVBRSITT) 


446  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

being  soluble  in  a  very  limited  class  of  solvents,  and  it  is  difficult  to  imag- 
ine a  solution  of  cinnabar  rising  through  several  miles  of  rock  at  constantly 
diminishing  temperatures  and  pressures  without  losing  a  large  part  of  its 
contents.  If  high  pressures  and  temperature  have  in  this  case  anything 
like  the  effect  which  the  theory  of  solutions  and  experiments  on  the  solu- 
bility of  substances  at  high  pressures  lead  one  to  suppose,  solutions  which 
below  the  granite  would  be  only  partially  saturated  would  become  super- 
saturated long  before  they  reached  the  surface,  and  cinnabar  deposits  thus 
formed,  if  they  cropped  out  at  all,  would  extend  down  into  the  granite, 
probably  growing  stronger  with  increasing  depth  for  long  distances.  This 
is  emphatically  not  the  case  with  the  deposits  of  the  Pacific  Slope. 

Hypothesis  of  derivation  from  granite. If,    On    the     Other    hand,    O11C    SUppOSCS    that 

the  granite  is  the  original  habitat  of  the  quicksilver,  the  observed  relations 
become  simple  and  natural.  The  solutions  of  sodium  sulphide  accompanied 
by  carbonates,  chlorides,  etc.,  which  followed  the  actual  course  of  lava  cur- 
rents, would  then  have  no  opportunity  to  take  up  quicksilver ;  while  simi- 
lar solutions  which  diverged  from  the  course  of  the  lava  into  the  surround- 
ing country  rock  would  decompose  the  metalliferous  components  of  the 
granite,  forming  and  dissolving  mercuric  and  ferric  sulphides  and  bringing 
them  to  the  surface  in  greater  or  smaller  quantities,  according  to  the  course 
of  the  currents  and  the  composition  of  the  granite.  Deposits  would  then 
form,  not  in  volcanic  vents  proper,  but  at  the  points  where  thermal  springs 
due  to  volcanic  action  issue  from  the  country  rock.  Such  deposits  would 
be  of  very  variable  size.  Where  the  channels  leading  up  to  the  springs 
were  simple  and  of  small  extent,  mere  traces  of  ore  would  reach  the  sur- 
face ;  while,  when  a  limited  system  of  openings  at  the  surface  gave  exit  to 
waters  which  had  flowed  through  extensive  masses  of  shattered  metallifer- 
ous granite,  larger  deposits  would  be  produced.  Now,  in  fact,  the  localities 
in  which  cinnabar  is  found  on  the  Coast  Ranges  are  numberless  ;  they  are 
characteristically  associated  with  hot  springs ;  they  do  not  occur  in  volcanic 
vents,  but  are  usually  at  no  great  distance  from  such  vents.  Of  all  the 
more  important  mines  New  Idria  alone  is  not  in  the  immediate  neighbor- 
hood of  lavas,  the  nearest  mass  of  basalt  known  being  some  ten  miles  dis- 
tant. But  hot,  alkaline  springs,  similar  to  those  immediately  associated 


DERIVATION  OF  CINNABAK  FEOM  GRANITE.  447 

with  volcanic  eruptions,  are  known  in  many  cases  to  reach  the  surface  at 
distances  as  great  as  this  from  lava  vents.  Though  the  cases  in  which  cin- 
nabar in  greater  or  smaller  quantities  occurs  close  to  hot  springs  in  the 
Coast  Ranges  are  numerous,  not  all  such  -springs  are  known  to  be  accom- 
panied by  quicksilver.  If  the  granite  be  supposed  to  be  the  source  of  the 
metal,  this  may  at  first  sight  seem  strange.  But  granite  is  by  no  means  a 
homogeneous  substance,  and,  as  I  have  pointed  out  in  Chapter  IV  and  else- 
where, was  probably  never  thoroughly  fluid.  With  reference  to  the  small 
quantities  of  heavy  metals  which  this  rock  is  known  to  contain  in  various 
European  localities,  the  composition  is  known  to  be  capricious.  It  is  alto- 
gether probable,  therefore,  that  some  parts  of  the  granite  underlying  the 
Coast  Ranges  may  contain  much  more  quicksilver  than  others,  and  this 
irregularity  of  diffusion,  in  combination  with  the  want  of  uniformity  in  the 
amount  of  granite  leached  by  different  hot  springs,  would  be  sufficient  to 
explain  all  the  observed  diversities  in  the  deposits  of  cinnabar. 

Evidence  at  steamboat  springs. —  At  Steamboat  Springs  a  variety  of  melals  oc- 
cur in  the  deposits  from  the  active  springs,  and  two  concurrent  quantitative 
analyses,  together  with  many  partial  analyses,  show  that  the  relative  quan- 
tities of  the  metals  are  as  follows,  beginning  with  the  largest:  antimony, 
arsenic,  lead,  copper,  quicksilver,  gold,  and  silver.  The  quantity  of  copper 
found  was  five  times  as  great  as  that  of  quicksilver.  If  these  same  metals 
could  be  found  in  the  granite  it  would  establish  the  highest  probability  that 
the  metals  of  the  deposits  were  derived  from  the  granite.  Analyses  of  large 
quantities  of  very  fresh  granite,  showing  no  effects  of  solfataric  action  and 
collected  half  a  mile  from  any  solfatarically  decomposed  material,  failed  to 
show  all  of  these  metals,  but  succeeded  in  revealing  the  presence  of  those 
most  abundant  in  the  deposits,  viz :  antimony,  arsenic,  lead,  and  copper. 
No  mercury  could  be  detected;  yet  the  fact  that  four  metals  are  common  to 
the  deposits  and  the  granite  and  the  coincidence  that  these  metals  are  the 
most  abundant  in  the  spring  deposits  are  highly  suggestive  of  derivation 
from  the  granite.  There  is  some  evidence  that  the  failure  to  find  quicksil- 
ver in  this  granite  was  due  to  irregularity  in  the  composition  of  the  massive 
rock.  The  only  portion  of  the  solfatarically  decomposed  area  of  Steamboat 
in  which  cinnabar  is  abundant  enough  to  be  visible  is  at  the  extreme  west 


448  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

em  edge  of  the  deposits.  The  quantity  of  quicksilver  at  their  eastern  edge, 
where  the  principal  active  springs  now  exist,  is  very  minute,  and  this  may  be 
due  to  the  composition  of  the  underlying  granite.  Now,  the  granite  subjected 
to  analysis  was  collected  about  half  a  mile  still  farther  east  than  the  active 
springs,  and  consequently  a  mile  and  a  half  from  the  mine  If  the  granite 
contains  quicksilver,  but  in  diminishing  quantities  as  one  proceeds  to  the 
east,  it  might  well  be  that  the  quantity  at  this  point  would  be  imperceptible. 
On  the  other  hand,  it  might  be  argued  that  the  presence  of  antimony,  arsenic, 
lead,  and  copper  in  both  the  granite  and  the  spring  deposits  is  a  mere  coin- 
cidence, that  the  infragranitic  source  of  the  ore  has  been  gradually  ex- 
hausted, and  that  consequently  only  the  older  deposits  show  considerable 
quantities  of  mercury.  This  argument  would  not,  however,  quite  fit  the 
facts,  for,  while  steam  and  hot  gases  still  issue  in  small  quantities  from  the 
mine,  there  is  a  belt  of  solfataric  matter  at  the  very  eastern  edge  of  area 
mapped  at  Steamboat.  The  springs  here  were  evidently  a  portion  of  the 
same  system  now  active,  but  here  neither  water  nor  steam  now  issues. 
These  eastern  springs  were  the  oldest  of  the  group,  yet  no  trace  of  quick- 
silver has  ever  been  detected  in  the  decomposed  mass.  If  the  quicksilver 
were  derived  from  a  limited  infragranitic  source,  these  eastern  localities 
should  show  ore  more  abundantly  than  any  other. 

Comparison    between    Steamboat    and   the    Comstock A    COmpaiMSOn      llHS     bCCll      HUlde 

on  page  352  between  the  character  of  the  deposit  of  Steamboat  Springs  and 
that  of  the  Comstock  lode,  six  miles  distant;  which  is  also  significant  in  the 
present  connection.  The  hanging  wall  of  the  Comstock  is  diabase,1  and 
I  have  adduced  much  evidence  going  to  prove  that  the  main  source  of  the 
ore  in  this  lode  is  this  Pre-Tertiary  eruptive  mass,  from  which  it  was  ex- 
tracted by  intensely  hot  waters  rising  from  great  depths,  charged  with  sul- 
phides and  carbonates  of  the  alkalis.2 

1  See  Geology  of  the  Comstock  Lode  and  Bull.  California  Acail.  Sci.  No.  C,  1886,  p.  94. 

sProf.  J.  S.  Newberry  has  made  a  curious  criticism  of  my  theory  of  the  ore  deposition  on  the  Com- 
stock (School  of  Mines  Quarterly,  vol.  5,  1884,  p.  338).  He  says :  "  Richthofen,  who  first  made  a  study 
of  the  Comstock  lode,  suggested  that  the  mineral  impregnation  of  the  vein  was  the  result  of  a  process 
like  that  described,  viz,  the  leaching  of  the  deep-seated  rocks,  perhaps  the  same  that  inclose  the  vein 
above,  by  highly  heated  solutions,  which  deposited  their  load  near  the  surface.  On  the  oth'T  hand, 
Becker  supposes  the  concentration  to  have  been  effected  by  surface  waters  (lowing  laterally  through  the 
igneous  rocks,  gathering  (lie  precious  metals  and  depositing  them  in  the  fissure."  The  inaccuracy  of  this 
statement  may  be  seen  from  the  following  quota!  ions.  Baron  Richlliofen  writes  (see  The  Comstock  Lode: 
Its  Character  etc.  or  Mon.  U.  8.  Geol.  Survey  No.  :t,  p.  !'.')  :  ''  Fluorine  and  chlorine  are  the  most  power- 


CONCLUSIONS.  449 

The  water  issuing  from  Steamboat  undoubtedly  comes  from  the  Sierra 
Nevada,  and  this  is  also  the  probable  origin  of  the  water  of  the  Comstock 
lode.  In  each  case  the  water  descends  to  great  depths  before  rising  to  its 
point  of  issue.  No\v,  if  the  ores  of  both  -localities  came  from  infragran- 
itic  sources,  these  sources  must  be  very  near  together,  but  of  very  differ- 
ent characters.  For  this  difference  it  is  not  easy  to  account.  But  if  only 
the  solvents  came  from  below  the  granite  and  the  metals  from  the  rocks 
comparatively  near  the  surface,  it  is  easy  to  see  why  the  two  deposits  differ 
as  they  do. 

Heavy  metais  in  granite. — "While  in  the  granite  investigated  for  this  memoir 
only  arsenic,  antimony,  copper,  and  lead  have  been  found;  lead  is  almost  or 
quite  always  argentiferous  and  silver  is  rarely,  if  ever,  free  from  gold.  Silver 
has  been  detected  by  Professor  Sandberger  in  the  mica  of  German  granites 
and  Mr.  Simundi  has  found  gold  in  the  granites  of  Idaho.  Gold  is  always 
accompanied  by  silver.  Zinc  also  has  been  found  in  gneiss-micas.  Arsenic, 
antimony,  lead,  and  copper  are  so  frequently  associated  in  nature  with  gold, 
silver,  and  zinc  as  to  lead  to  the  supposition  that  they  often  have  a  common 
source.  Mercury  is  not  yet  known  as  a  component  of  granite  or  gneiss,  but 
all  the  metals  associated  with  it  have  been  detected  in  these  rocks.  The 
probability  that  the  quicksilver  alone  is  derived  from  an  infragranitic  source 
is  exceedingly  small  and  is  not  supported  by  a  single  known  fact. 

conclusions. —  The  evidence  is  overwhelmingly  in  favor  of  the  supposition 
that  the  cinnabar,  pyrite,  and  gold  of  the  quicksilver  mines  of  the  Pacific 
slope  reached  their  present  positions  in  hot  solutions  of  double  sulphides, 

i'nl  volatili/ers  known,  and  form  volatile  combinations  with  almost  every  substance.  Besides  silicon, 
the  metals  have  a  great  at'linity  with  them.  All  those  which  occur  in  the  Comstock  vein  could  ascend 
in  a  gaseous  .state  in  combination  with  one  or  other  of  them.  They  must  then  be  precipitated  in  the 
upper  parts  as  metallic  oxides  or  chlorides,  and  in  the  native  state.  Thus  the  fissure  was  gradually 
tilled,  from  its  upper  portion  downwards,  with  all  the  elements  which  wo  find  chemically  deposited  in 
it."  In  my  report,  page  iiHli,  I  wrote  :  "  Floods  of  heated  waters  now  rose  from  a  depth  of  two  or  more 
miles,  certainly  carrying  carbonic  and  sulphydric  acids,  and  possibly  other  active;  re;igeuts,  in  solution. 
The  water  followed  the  course  of  the  main  fissure  as  closely  as  circumstances  permitted,  but  was  de- 
llectcd  to  a  great  extent  into  the  fractured  mass  of  the  east  country,  where  decomposition  resulted. 
Silica  and  metallic  sails  were  set  free  from  the  mineral  constituents  of  the  rock,  and  were  carried  into 
the  comparatively  open  spaces  near  the  main  fissure,  where  they  were  redepositcd"  (see.  also,  ibid.,  pp. 
•£if>.  ii83,  ;!8fi,  3'JO).  J'roi'essor  NY  wherry  attributes  to  von  Kichthofeii  and  himself  approves  the  very 
theory  which  I  was  at  great  pains  to  support.  The  hypothesis  which  von  Kichthofeii  advocates  New- 
berry  seems  entirely  to  have  overlooked  (see,  also,  The  genesis  of  certain  ore  deposits,  by  S.  F.  Emmous  : 
Trans.  Am.  last.  Miu.  Kng.,  vol.  15,  1H-7,  p.  125). 

MON   XIII 29 


450  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

which  were  leached  out  from  masses  underlying  the  granite  or  from  the 
granite  itself.  No  one  fact  or  locality  absolutely  demonstrates  whether  the 
metals  were  originally  components  of  the  granite  or  came  from  beneath  it, 
but  the  tendency  of  the  evidence  at  all  points  is  to  show  that  granite  yielded 
the  metals  to  solvents  produced  by  volcanic  agencies,  and,  when  all  the 
evidence  is  considered  together,  it  is  found  that  this  hypothesis  explains  all 
the  known  circumstances  very  simply,  while  the  supposition  of  an  infra- 
granitic  origin  leads  to  numerous  difficulties.  Though  no  one  of  these  may 
be  by  itself  fatal,  when  taken  as  a  whole  they  appear  to  be  so.  As  there 
is  no  known  direct  evidence  pointing  to  an  infragranitic  origin  of  the  quick- 
silver and  the  gold,  I  consider  it  tolerably  well  established  that  both  were 
actually  derived  from  the  granite. 

I  regard  many  of  the  gold  veins  of  California  as  having  an  origin  entirely 
similar  to  that  of  the  quicksilver  deposits.  I  also  have  some  reason  to  sup- 
pose that  some  of  the  gold  deposits  were  formed  by  the  leaching  of  their  walls 
by  surface  waters.  The  auriferous  area  is  now  under  examination,  and  the 
investigations  on  ore  deposits  described  in  this  volume  will  be  continued  and 
extended  in  connection  with  my  survey  of  the  gold  belt. 


CHAPTER  XVII. 

SUMMARY  OF  RESULTS. 

Purpose  of  this  chapter. — A  very  large  portion  of  the  foregoing  pages  is  nec- 
essarily occupied  by  detailed  descriptions,  written  in  order  to  enable  readers 
to  judge  whether  the  facts  warrant  the  opinions  expressed,  and  by  discus- 
sions of  a  somewhat  technical  character.  There  may  be  those,  however, 
who  will  be  interested  to  know  in  brief  what  conclusions  have  been  reached, 
but  who  have  no  inclination  to  undertake  the  somewhat  serious  task  of 
weighing  the  evidence  adduced  and  of  following  the  arguments  in  detail. 
For  such  readers  this  chapter  is  written ;  but  it  must  be  understood  that 
for  full  and  fully  qualified  statements  reference  must  be  made  to  the  body 
of  the  report. 

statistics  and  history. — The  commercial  status  of  quicksilver  is  peculiar.  It 
seems  to  be  three  or  more  times  as  abundant  in  nature  as  silver,  and  since 
1850  the  weight  of  silver  extracted  is  about  six-tenths  that  of  quicksilver; 
but  the  total  value  of  the  latter  is  less  than  one-sixteenth  that  of  the  former 
metal.  This  is  due  to  the  limited  demand  for  mercury,  which  is  employed  in 
large  quantities  only  for  amalgamating  gold  and  silver  ores  and  for  the  man- 
ufacture of  vermilion.  If  it  should  prove  practicable  to  extirpate  phylloxera 
with  mercury,  this  application  will  greatly  benefit  the  quicksilver  miners  as 
well  as  the  vine-growers. 

• 

Five  regions  iu  the  world  are  yielding  or  have  yielded  great  quantities 
of  this  metal.  They  are  Almaden,  in  Spain;  Idria,  in  Austria;  Kwei-Chau, 
in  China;  Huancavelica,  in  Peru,  and  the  Coast  Ranges  of  California.  Of 
the  Chinese  region  little  is  known,  except  that  it  is  extremely  rich;  in  the 
opinion  of  a  very  competent  judge,  the  richest  of  all.  Almaden  has  pro- 

451 


452  QUICKSILVER  DEPOSITS  OF  TBE  PACIFIC  SLOPE. 

duced  more  than  any  one  of  the  other  three.  Idria,  Huancavelica,  and  Cali- 
fornia have  each  yielded  pretty  nearly  the  same  aniount  from  the  dates  of 
discovery  of  the  deposits  to  the  present  day,  California  taking  the  lowest 
rank.  But  considering  only  the  period  which  has  elapsed  since  the  mines 
of  the  Pacific  Slope  were  first  opened  the  case  is  different.  Peru  produced 
nothing  from  1850  to  1886;  Idria,  in  round  numbers,  300,000  flasks ;  Alma- 
den,  1,140,000;  and  California,  1,400,000,  or  nearly  half  the  entire  product 
of  the  world.  But  California  does  not  seem  likely  to  maintain  the  same  rank 
among  quicksilver  producers  in  the  future. 

Quicksilver  was  first  recognized  in  California  as  occurring  at  the  crop- 
pings  of  the  New  Almaden  mine  by  Andreas  Castillero  in  1845.  His 
means  of  testing  the  ore  were  quaint,  but  effectual,  and  he  immediately 
began  production  on  a  small  scale.  A  large  number  of  other  deposits  were 
discovered  at  later  dates,  and  some  forty  mines  have  produced  metal,  though 
from  some  of  these  the  yield  has  been  trifling.  Half  a  dozen  of  them 
have  yielded  from  40,000  flasks  upward  and  New  Almaden  has  turned  out 
over  853,000.  The  sketch  map  of  California  (see  Plate  I)  shows  the  dis- 
tribution of  some  of  the  mines. 

Foreign   occurrences   of  quicksilver. TllC     aCCOlint     givetl     of     deposits     kllOWIl     tO 

occur  in  foreign  countries  will  not  bear  condensation,  being  in  itself  a  brief 
digest.  The  rocks  inclosing  quicksilver  deposits  are  of  very  diverse  ages, 
ranging  all  the  way  from  Archaean  granites  and  schists  to  recent  strata  and 
lavas.  The  lithological  variety  of  the  inclosing  rocks  is  equally  great, 
including  limestones,  sandstones,  and  shales,  many  kinds  of  metamorpliic 
strata,  and  massive  rocks  of  acid,  neutral,  and  basic  types.  Cinnabar  does 
not  even  seem  to  exhibit  any  preference  for  one  class  of  rocks  rather  than 
another.  It  is  clear  that  the  mere  age  of  the  surrounding  material  is  with- 
out influence  on  the  deposition  of  the  ore  and  that  the  ore  cannot  in  gen- 
eral be  derived  from  the  walls  of  the  deposits,  for  it  isVarcely  auppoaable 
that  this  metal  forms  an  original  constituent  of  all  sorts  of  rocks. 

A  glance  at  the  map  (Plate  II)  shows  that  the  quicksilver  deposits 
occur  along  the  great  axes  of  disturbance  of  the  world.  One  of  these  is  on 
the  line  of  the  principal  mountain  system  of  Kurasia,  for  which  I  suggest 
the  Hi;  me  of  Alpimalayan  chain,  because  it  includes  the  Alps  and  the  Hima- 


SUMMARY.  453 

layas.  The  other  coincides  with  the  western  ranges  of  the  Cordillera  system 
of  America.  In  many  parts  of  the  world  volcanic  phenomena  are  intimately 
associated  with  these  axes  of  disturbance  and  with  the  quicksilver  deposits. 
The  minerals  which  occur  in  considerable  quantities  with  quicksilver 
ores  are  few  in  number.  Pyrite  or  marcasite  is  nearly  or  quite  always 
present,  arsenic  and  antimony  are  found  at  many  localities,  and  copper 
ores  sometimes  accompany  cinnabar.  Other  metalliferous  minerals  are 
comparatively  rare.  The  principal  gangue  seems  to  be  invariably  either 
silica,  sometimes  hydrous,  or  carbonates,  chiefly  calcite.  Cinnabar  occurs 
in  true,  simple  fissure  veins,  in  impregnations,  and  stockworks.  The  forms 
which  its  deposits  take  do  not  apparently  differ  in  any  essential  respect 
from  those  which  deposits  of  other  metals  assume;  but  ore  bodies  precipi- 
tated by  substitution  do  not  appear  from  the  descriptions  to  be  common. 
In  all  cases  a  fissure  system  seems  probably  associated  with  the  deposits. 

The  facts  recorded  point  to  the  supposition  that  most  of  the  quicksilver 
deposits,  if  not  all  of  them,  have  been  formed  in  a  similar  manner.  They 
have  all  been  deposited  from  solution,  for  the  gangue  minerals  could  have 
been  formed  in  no  other  way.  Cinnabar  has  certainly  been  deposited  by 
thermal  springs  of  very  high  temperature  at  Puzzuoli,  in  Italy,  and  at  Lake 
Omapere,  in  New  Zealand,  and  is  most  intimately  associated  with  hot 
springs  and  other  volcanic  phenomena  at  a  large  number  of  other  points. 
It  has,  perhaps,  always  been  deposited  by  heated  waters.  It  must  be 
derived  from  some  deep-seated  substance  of  world-wide  distribution,  which 
has  been  exposed  to  the  action  of  volcanic  solvents  by  profound  disturb- 
ance. The  fundamental  granitoid  rocks  answer  this  description,  for  they 
si-cm  everywhere  to  underlie  all  other  rocks  ;  they  are  of  great  but  unknown 
thickness,  and  they  certainly  in  part  overlie  the  centers  of  volcanic  activity. 
Geological  investigations  have  as  yet  revealed  no  other  substance  of  similar 
distribution.  There  is  no  other  rock  from  which  it  is  equally  probable  that 
the  quicksilver  is  derived. 

The  sedimmtary  rocks. —  Excepting  the  light  cream-colored  schists  of  Miocene 
age,  which  occupy  a  narrow  strip  along  the  coast  of  California  from  the 
neighborhood  of  Santa  Cruz  southward,  the  rocks  of  the  Coast  Ranges 
where  unaltered  are  mainly  sandstones  of  Cretaceous  and  Tertiary  age. 


454  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Sandstones  often  occur  here  in  practically  uninterrupted  series  of  beds 
many  thousands  of  feet  in  thickness.  The  unaltered  sandstones  of  the 
Coast  Ranges  are  very  much  alike,  whatever  their  age.  The  Tejon  (Eocene) 
beds,  however,  are  of  a  much  lighter  color  than  the  Chico  (late  Cretaceous) 
or  the  Miocene  rocks.  The  Chico  again  is  usually  more  indurated  than  the 
Miocene.  While  the  Knoxville  (Neocomian)  sandstones  where  unaltered 
closely  resemble  those  of  later  periods,  no  case  is  known  in  which  unaltered 
Knoxville  beds  are  not  intimately  associated  with  greatly  disturbed  and 
metamorphosed  rocks  of  the  same  age,  so  that  there  is  no  difficulty  in  dis- 
crimination when  once  it  is  established  that  the  epoch  of  violent  upheaval 
and  metamorphism  followed  soon  after  the  close  of  the  Knoxville. 

Field  study  showed  that  the  Coast  Ranges  are  probably  everywhere 
underlain  by  granite.  The  microscopical  examinations  have  given  this  in- 
ference unexpectedly  strong  confirmation,  for,  though  on  structural  grounds 
it  appears  certain  that  a  portion  of  the  later  sandstones  were  formed  at  the 
expense  of  earlier  arenaceous  beds,  they  all  exhibit  unmistakable  evidence 
of  granitic  origin.  They  are  thus  so  similar  that  they  may  be  discussed 
together  lithologically.  The  microscope  shows  that  the  main  constituents 
are  quartz  fragments  (containing  abundant  fluid  inclusions  and  in  other 
respects  resembling  the  quartzes  of  the  underlying  granite),  orthoclase,  the 
same  plagioclases  found  in  the  granite,  and  biotite.  Most  of  the  less  impor- 
tant constituents  of  the  granite  are  also  found  in  the  sandstones.  The  pro- 
portion of  quartz  in  the  sandstones  is,  as  a  matter  of  course,  greater  than  in 
the  granite.  The  grains  are  commonly  rounded  like  ordinary  beach  sand, 
but  are  sometimes  extremely  sharp.  The  cement  is  largely  calcite.  The 
sandstones  are  subject  to  the  ordinary  decomposition  known  as  weathering, 
by  which  the  ferromagnesian  silicates  are  in  part  converted  to  chlorite  and 
in  part  to  a  ferruginous  cement 

The  unmetamorphosed  late  Cretaceous  and  Miocene  sandstones  show 
numerous  concretions.  These  in  rare  instances  contain  fossils  as  nuclei. 
A  representative  concretion  in  which  no  organic  remains  existed  was  inves- 
tigated. It  was  found  that  the  cementing  matrix  contained  a  considerable 
amount  of  phosphoric  acid,  but  was  chiefly  composed  of  a  mixture  of  cal- 
cium carbonate  and  a  hydrous  subsilicate  of  iron.  It  is  shown  that  this 


SUMMAKY.  455 

composition  points  to  the  action  of  organic  acids,  especially  the  humus 
acids,  and  that  the  class  of  concretions  of  which  this  is  a  type  must  have 
contained  nuclei  of  organic  matter  which  have  decomposed  and  disap- 
peared. 

Rounded  nodules  resulting  from  the  action  of  decomposition  processes 
on  angular  masses  are  discussed,  and  it  is  shown  that  the  rapidity  of  attack 
must  be  in  an  inverse  ratio  to  the  radius  of  curvature  of  the  mass.  This 
explains  the  fact  that  such  nodules  tend  to  a  spherical  form.  The  rounding 
of  pebbles  and  of  sand  grains  is  shown  to  depend  on  the  same  mathemat- 
ical law. 

Sharply  denned  limits  cannot  be  drawn  between  the  various  early  Cre- 
taceous metamorphosed  rocks  of  the  Coast  Ranges;  they  pass  over  into  one 
another  by  degrees.  For  purposes  of  description,  however,  it  is  desirable 
to  consider  certain  types  as  distinct.  The  divisions  which  appear  to  satisfy 
best  both  their  field  occurrence  and  their  microscopical  character  are  as 
follows :  Partially  metamorphosed  sandstones,  in  which,  although  a  process  of 
recrystallization  has  begun,  the  clastic  structure  as  seen  under  the  micro- 
scope is  not  obliterated,  but  is  often  more  or  less  obscured.  This  class  will 
be  referred  to  hereafter  for  the  sake  of  brevity  as  altered  sandstones.  Gran- 
ular metamorphics,  in  which  metasomatic  recrystallization  of  sandstones  has 
transformed  the  mass  into  a  holocrystalline  aggregate,  form  another  group. 
The  third  class  embraces  the  ylaueopliane  schists,  derived  from  certain  shales, 
much  as  the  granular  metamorphics  are  produced  from  sandstone.  The 
plif/Hiiii/ex  are  a  series  of  more  or  less  calcareous,  schistose  rocks  which  have 
been  subjected  to  a  process  of  silicification,  resulting  in  chert-like  masses, 
which  retain  schistoid  structure  and  are  intersected  by  innumerable  quartz 
veins.  They  usually  carry  more  or  less  zoisite.  Finally  the  serpentines, 
which  have  resulted  in  part  from  the  direct  action  of  solutions  on  sandstones 
and  in  part  from  alteration  of  the  granular  metamorphics. 

A  considerable  number  of  minerals  have  been  generated  in  these  rocks 
by  metasomatic  processes  and  weathering.  These  are  biotite,  muscovite, 
augite.  hornblende,  glaucophane,  labradorite,  andesine  (probably),  oligo- 
clase,  albite,  orthoclase,  quartz,  zoisite,  rutile,  ilmenite,  titanite,  apatite, 
garnet,  nacrite,  chlorite,  epidote,  serpentine,  and  chromite.  The  most  inter- 


456  QUICKSILVER  DEPOSITS  OP  THE  PACIFIC  SLOPE. 

esting  and  in  some  respects  the  most  important  mineral  found  is  zoisite, 
which  has  been  repeatedly  analyzed  and  tested. 

All  the  more  important  processes  of  metasomatic  recrystallization  can 
be  traced  in  the  altered  sandstones,  rocks  whoso  clastic  origin  could  not 
be  doubted  for  a  moment.  In  many  cases  one  of  the  first  stages  in  the 
process  is  the  resolution  of  the  clastic  grains  into  crystalline  aggregates 
from  which  new  minerals  are  again  built  up.  Augite,  hornblende,  and 
plagioclase  have  been  observed  which  had  formed  in  this  manner.  The 
feldspars  also  crystallize  along  tiny  veins  in  the  slides.  A  frequent  occur- 
rence is  the  resolution  of  quartz  grains  into  plagioclase  microlites.  The 
reaction  begins  on  the  surface  of  the  quartz  grains  and  produces  a  fringe  of 
twinned  feldspar  microlites  in  positions  approximately  normal  to  the  surface 
of  the  residual  kernel.  The  microlites  do  not  merely  abut  against  the  ker- 
nel, but  penetrate  it  fora  sensible  distance  like  closely  set  pins  in  a  cushion. 
Zoisite  is  present  in  nearly  all  the  altered  sandstones.  It  forms  in  the  ag- 
gregates which  result  from  the  clastic  grains,  and  its  microlites  sometimes 
pierce  quartz  grains  from  the  outside.  It  is  abundant  in  the  granular  as 
well  as  in  the  prismatic  form.  This  hydrous  mineral  forms  simultaneously 
with  the  other  products  of  metasomatic  recrystallization,  and  does  not  here 
represent  a  decomposition  process  in  rocks  already  recrystallized. 

It  is  only  necessary  to  suppose  the  processes  indicated  above  carried 
further  to  obtain  a  product  in  which  the  clastic  character  of  the  rocks  would 
cease  to  be  evident.  The  altered  sandstones  thus  form  under  the  micro- 
scope, as  they  do  in  the  field,  transitions  from  the  clastic  series  to  the  holo- 
crystalline  rocks. 

The  granular  metamorphic  rocks  of  the  Coast  Ranges  are  separable 
under  the  microscope  into  several  groups,  but  this  is  not  practicable  by 
unaided  vision  ;  indeed,  there  are  many  cases  in  which  specimens  which 
appear  to  the  naked  eye  to  be  not  greatly  altered  sandstones  prove  under 
the  microscope  to  be  holocrystalline  rocks,  with  none  of  the  microstructure 
of  a  sandstone.  The  most  important  class  of  the  granular  rocks  is  chiefly 
composed  of  plagioclase  and  augite.  It  sometimes  resembles  true  diabase, 
and  may  conveniently  be  called  pseiiilixlidbase.  The  pyroxene  sometimes 
assumes  the  form  of  diallage.  Another  class  contains  amphibole  instead  of 


SUMMARY.  457 

pyroxene,  and  I  call  this  rock  pseudodiorite.  No  metamorphic  rocks  have 
been  found  in  place  which  carry  olivine.  Glaucophane  occurs  in  both  the 
pseudodiabase  and  tire  pseudodiorite.  The  quantity  of  zoisite  in  these  rocks 
is  very  variable  and  in  some  cases  is  so  grealthat  with  feldspar  it  forms  almost 
the  entire  mass.  The  schistose  metamorphics,  not  including-  phthanites,  are 
all  characterized  by  the  presence  of  glaucophane.  In  every  case  but  one, 
zoisite  is  associated  with  the  glaucophane  in  this  group  and  either  muscovite 
or  biotite  is  usually  present. 

The  phthanites  or  silicified  shales  form  a  very  distinct  group  readily 
distinguishable  from  the  granular  metamorphics.  They  are  usually  green 
or  brown  and  are  intersected  by  innumerable  quartz  veins.  They  con- 
tain microscopic  organic  remains,  and  embedded  in  the  quartz  veins  or  pro- 
jecting from  their  walls  are  often  numerous  zoisite  crystals.  All  of  these 
rocks  are  best  represented  by  detailed  descriptions  of  special  examples,  for 
which  there  is  no -space  here. 

Serpentine  in  a  comparatively  pure  state  occurs  throughout  the  quick- 
silver belt  in  irregular  areas.  As  nearly  as  can  be  estimated  these  areas 
amount  to  somewhat  over  one  thousand  square  miles  between  Clear  Lake 
and  Xew  Idria.  Serpentine  is  also  one  of  the  mineral  constituents  of  many 
of  the  altered  sandstones  and  of  the  granular  metamorphic  rocks.  It  is  a 
biaxial  variety,  often  just  perceptibly  dichroitic,  and  rarely  shows  differ- 
ences of  tint  as  great  as  those  characteristic  of  chlorite.  It  might  be  called 
antigorite  if  it  seemed  needful  to  separate  the  biaxial  serpentines.  The  net 
structure  so  usual,  though  not  invariable,  in  serpentine  formed  from  olivine 
has  nowhere  been  detected.  Where  any  considerable  quantity  of  serpen- 
tine is  present  it  usually  shows  the  now  well  known  grate  structure. 

No  considerable  portion  of  the  serpentine  of  the  Coast  Ranges  has 
resulted  from  the  decomposition  of  olivine.  Only  in  one  district  have 
pebbles  of  olivine  gabbro  have  been  found,  and  these  contain  a  mere  trace 
of  serpentine,  while  the  origin  of  the  serpentine  has  been  traced  in  a  great 
number  of  cases  to  rocks  containing  no  olivine. 

Field  observations  show  most  conclusively  that  the  great  mass  of  the 
serpentine  of  this  area  is  derived  from  the  sandstones,  either  immediately 
or  through  an  intermediate  granular  metamorphic  rock. 


458  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

Under  the  microscope  it  can  be  shown,  as  I  think  beyond  question, 
that  all  of  the  principal  components  of  the  sandstones  and  granular  meta- 
morphic  rocks  are  subject  to  serpentinization.  Not  only  are  the  augite  and 
hornblende  subject  to  this  kind  of  decomposition,  but  feldspar,  quartz,  apa- 
tite, and  probably  other  minerals  are  also  converted  into  serpentine. 

In  the  present  state  of  opinion  it  is  not  superfluous  to  insist  upon  the 
derivative  character  of  the  holocrystalline  metamorphic  rocks  and  the  ser- 
pentine of  the  quicksilver  belt.  There  are  in  fact  two  independent  lines  of 
evidence  leading  to  this  conclusion,  for  the  known  occurrences  of  zoisite 
and  its  composition  indicate  that  rocks  containing  it  otherwise  than  as  a 
product  of  decomposition  are  metamorphic,  while,  even  if  zoisite  were  a 
common  constituent  of  undecomposed  lavas,  the  proof  of  the  metamorphic 
character  of  these  rocks  would  still  be  ample. 

The  depth  at  which  the  rocks  now  exposed  were  buried  at  the  epoch 
of  metamcrphism,  soon  after  the  close  of  the  Neocomian,  was  probably  a 
moderate  one,  perhaps  two  thousand  or  three  thousand  feet.  At  a  sufficient 
pressure  rocks  appear  to  be  molded  by  dynamic  action  rather  than  crushed, 
and  Dr.  Lehmann  has  shown  that  under  such  conditions  even  crystals  may 
be  bent.  In  the  Coast  Ranges  no  such  phenomenon  has  been  observed. 
On  the  contrary,  the  amount  of  fracturing  is  really  astonishing.  The  re- 
crystallization  of  the  sandstones  and  the  serpentinization  and  silicification 
are  regarded  as  due  to  the  action  of  solutions  rising  from  the  underlying 
granite;  and  these  solutions  were  heated,  charged  with  mineral  matter, 
and  driven  to  the  surface  as  a  result  of  the  same  dynamical  causes  which 
produced  the  uplift. 

In  conclusion  it  may  be  noted  that  all  the  more  important  minerals  of 
the  Archaean  schists  are  found  in  the  matamorphosed  rocks  of  the  Coast 
Ranges  The  quantitative  relations  indeed  are  different,  especially  those  of 
the  feldspars;  for,  while  orthoclase  predominates  in  the  Archaean,  plagio- 
clase  is  much  more  common  in  the  Coast  Ranges;  but  it  is  evident  that, 
under  conditions  not  greatly  dissimilar  to  those  which  prevailed  in  Califor- 
nia at  the  close  of  the  Neocomian,  rocks  not  distinguishable  from  those  of 
Archaean  areas  might  have  been  formed. 


SUMMARY.  459  : 

The  massive  rocks. — The  massive  rocks  met  with  in  this  investigation  are 
granite,  diabase,  diorite,  andesites,  rhyolite,  and  basalt.  The  granites  seem 
to  underlie  the  entire  Coast  Ranges  and  to  form  the  lower  and  central  por- 
tion of  the  Sierra  Nevada.  They  are  on  fhe~whole  pretty  uniform  and  pre- 
sent no  known  peculiarity.  Diabase  occurs  in  the  Mesozoic  conglomerates 
of  Steamboat  Springs  and  seems  to  be  identical  with  the  diabase  which 
forms  the  hanging  wall  of  the  Comstock  lode.  Diorite  is  represented 
chiefly  by  pebbles  in  the  Neocomian  conglomerates  of  the  Coast  Ranges. 

The  andesites  are  divisible  into  two  groups,  an  older  and  a  younger. 
The  younger  group  is  found  at  Steamboat  Springs  and  elsewhere  in  and 
near  the  Sierra  Nevada,  at  Mt.  Shasta,  and  from  Clear  Lake  to  Mt.  Diablo. 
It  presents  several  varieties :  one  containing  pyroxene,  a  mere  trace  of 
hornblende,  and  no  mica;  a  second  containing  pyroxene  and  mica,  but  no 
hornblende;  a  third  containing  hornblende,  with  very  small  quantities  of 
.pyroxene,  together  with  mica  in  quantities  ranging  from  nil  to  a  very  large 
perrontage.  All  of  these  pass  over  into  one  another,  sometimes  within  a  few 
feet,  and  in  masses  evidently  not  due  to  separate  eruptions.  Nearly  or  quite 
all  of  them  are  rough,  soft  rocks,  such  as  were  formerly  supposed  to  be 
trachyte.  They  form  a  natural  group,  which  should  be  recognized.  I  have 
proposed  the  name  axperite  to  suggest  their  resemblance  to  trachyte.  As- 
pcrik's,  then,  are  a  group  of  andesites  with  external  characteristics  similar 
to  those  of  trachyte.  • 

Both  the  asperites  and  the  basalts  near  Clear  Lake  pass  by  transitions 
into  enormous  masses  of  obsidian.  The  transitions  have  been  traced  in  the 
field,  in  the  chemical  laboratory,  and  under  the  microscope.  The  glasses  are 
more  acid  than  the  crystalline  rocks  into  which  they  pass,  but  they  contain 
much  more  alkali  and  much  less  lime  and  magnesia;  their  specific  gravity 
is  also  much  smaller.  They  have  cooled  as  glasses,  instead  of  as  crystalline  \ 
aggregates,  because  of  their  peculiar  composition,  and  not  because  they  have 
been  subjected  to  different  physical  conditions  from  the  associated,  sensibly 
holocrystalline  lavas. 

The  origin  of  the  massive  rocks  of  California  is  discussed  in  Chapter 
IV.  It  is  shown  to  be  probable  that  portions  of  the  granitic  rocks  repre- 
sent parts  of  the  original  crust  of  the  earth^or  that  they  are  primeval  rocks. 


400  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

That  the  primeval  rocks  must  underlie  all  others  is  self-evident  and  the 
lowest  rocks  we  know  of  are  granitic.  It  has  never  been  shown  how  the 
original  crust  could  be  wholly  buried  beneath  its  own  ruins,  and  simple 
arguments  are  adduced  to  show  this  utterly  improbable.  It  follows  that  a 
part  of  the  granite  must  be  Azoic  and  that  the  lavas  which  have  broken 
through  the  granite  cannot  be  remelted  sediments. 

Historical  geology. — The  following  outline  states  in  the  briefest  terms  the 
main  events  in  the  geological  history  of  the  Coast  Ranges,  so  far  as  they 
have  been  elucidated  by  former  observers  and  by  myself. 

Prior  to  the  opening  of  the  Cretaceous  the  region  of  the  Coast  Ranges 
seems  to  have  been  chiefly  occupied  by  granite.  During  the  first  period 
of  the  Cretaceous — the  Neocomian — great  quantities  of  sediments  derived 
from  the  granite  were  deposited  on  the  quicksilver  belt.  These  were  chiefly 
sands,  though  shales  and  calcium  carbonate  were  also  found.  The  sea  must 
have  been  shallow  and  many  islands  must  have  existed  in  it.  The  most 
characteristic  animals  of  the  period  were  Ance.Ha  concentrica  and  Anc/'Ha 
mosquensis,  of  which  a  description,  with  illustrations,  by  Dr.  C.  A.  White,  is 
given  in  Chapter  V.  At  the  close  of  the  Neocomian  an  upheaval  took 
place  with  extraordinary  violence,  folding  and  crushing  the  rocks  and  pro- 
ducing the  first  ranges  along  the  coast  of  California  of  which  any  record 
remains.  It  is  probable  enough  that  earlier  ranges  existed,  but  had  been 
obliterated.  The  same  upheaval  affected  the  Sierra  Nevada  and  added  to 
its  western  side,  along  a  part  of  the  gold  belt,  an  immense  mass  of  Neo- 
comian rocks,  which  were  driven  into  a  nearly  vertical  position.  Accom- 
panying this  upheaval  was  a  vast  expenditure  of  energy.  The  heat  into 
which  this  energy  was  converted  brought  about  the  solution  of  some 
components  of  the  underlying  granite,  particularly  of  magnesia  and  soda. 
These  solutions,  acting  on  the  Neocomian  rocks,  converted  them  into  the 
metamorphic  product  mentioned  in  preceding  paragraphs. 

During  the  Middle  Cretaceous  (the  Turonian)  the  shore  of  California 
seems  to  have  been  nearly  in  the  same  position  as  it  now  is,  and  a  series 
of  beds  discovered  during  this  investigation,  the  Wallala  group,  was  de- 
posited. They  are  composed  of  granitic,  detritus  and  fragments  of  meta- 

morphosed  Neocomian  beds  and  certain  fossils. 

1 


SUMMARY.  461 

Late  in  the  Cretaceous  a  great  part  of  the  Coast  Ranges  was  again 
under  water  and  the  sea  once  more  reached  the  flanks  of  the  Sierra  Ne- 
vada. The  sediments  laid  down  at  that  time,  and  now  known  as  the  Chico 
series,  were  of  course  deposited  unconforuiably  upon  the  metamorphosed 
and  eroded  Neocomian  rocks.  There  was  no  disturbance  at  the  close  of 
the  Cretaceous,  and  sedimentation  and  the  gradual  development  of  the  ma- 
rine fauna  went  on  undisturbed  through  the  Eocene,  which,  in  California, 
is  represented  by  the  Tcjon  series.  The  non-conformity  between  the  Chico 
and  the  underlying  rocks  and  the  continuity  of  the  Chico  and  Tejon  were 
first  established  in  this  investigation. 

Between  the  Eocene  and  Miocene  there  is  a  sharp  faunal  distinction, 
but  there  is  no  general  corresponding  non- conformity.  At  the  close  of  the 
Miocene  an  important  upheaval  took  place,  though  one  which  was  much  less 
violent  than  the  earlier  uplift.  Professor  Whitney  first  studied  this  Post- 
Miocene  disturbance.  Only  a  small  amount  of  Pliocene  territory  exists  in 
this  region,  and  part  of  ii  consists  of  lake  deposits.  It  is  of  course  uncou- 
formable  with  the  Miocene. 

After  the  close  .of  the  Jurassic  no  eruptions  seem  to  have  taken  place 
in  the  Coast  Ranges  until  the  close  of  the  Miocene,  or  possibly  a  little 
later.  Avuk'sites  were  then  ejected  and  outbursts  of  these  rocks  recurred 
at  intervals  to  the  close  of  the  Pliocene.  The  asperites  of  Clear  Lake  and 
of  Mt.  Shasta  date  from  the  end  of  the  Pliocene.  Only  one  dike  of  rhy- 
olite  is  known  to  exist  in  the  Coast  Ranges.  It  is  close  to  the  New  Alma- 
den  mine.  It  is  probably  later  than  the  andesites,  but  its  date  is  not  cer- 
tain. During  the  Quaternary  and  down  to  very  recent  times  there  have 
been  many  basalt  eruptions. 

The  formation  of  cinnabar  deposits  was  confined  to  the  period  of  vol- 
canic eruptions  with  which  they  are  most  intimately  connected.  Almost 
all  the  massive  and  sedimentary  rocks  of  the  region  inclose  bodies  of  cin- 
nabar, and  the  age  and  the  chemical  character  of  the  rocks  are  without  ap- 
parer.t  influence  on  the  ore. 

ciear  Lake  district. — The  region  of  Clear  Lake  is  a  picturesque  one,  lying  at 
the  northwestern  extermitv  of  a  belt  of  lavas  which  extend  southward  as  far 

«.' 

as  the  Bay  of  San  Francisco.     Extinct  volcanic  cones,  borax  lakes,  hot 


462  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

mineral  springs,  and  deposits  of  sulphur  and  cinnabar  form  its  most  note- 
worthy features. 

Metamorphic  rocks  of  the  Neocomian  series  underlie  the  whole  country 
so  far  as  known,  though  the  existence  of  granite  pebbles  in  the  stream 
which  drains  the  lake  suggests  that  this  rock  is  exposed  at  no  great  distance. 
Upon  a  part  of  the  metamorphic  area  about  Lower  Lake  the  Ghico-Tejon 
occurs.  The  latter  series  is  comparatively  little  disturbed  and  not  meta- 
morphosed. 

The  earliest  eruptions  .in  the  district  seem  to  have  been  that  of  Chalk 
Mountain,  on  the  north  fork  of  Cache  Creek,  and  some  of  the  rock  near 
Thurston  Lake.  This  lava  was  a  dense  pyroxene-andesite  and  the  eruption 
seems  to  have  occurred  about  the  beginning  of  the  Pliocene.  Soon,  and 
perhaps  immediately  afterward,  a  large  body  of  fresh  water  formed,  which  I 
have  called  Cache  Lake.  It  lay  mostly  to  the  east  of  Clear  Lake  and  con- 
tinued in  existence  up  to  the  end  of  the  Pliocene.  At  this  period  fresh  erup- 
tions of  andesites  took  place.  They  are  the  asperites  of  Mt.  Konocti  (or 
Uncle  Sam)  and  the  neighborhood.  A  part  of  the  lava  flowed  over  a  portion 
of  the  bed  of  Cache  Lake,  and  the  orography  was  so  modified  as  to  shift  the 
position  of  the  water  to  the  new  Clear  Lake,  which  overlaps  part  of  the 
more  ancient  bed.  The  change  must  have  been  somewhat  gradual,  for  the 
same  mollusks  which  lived  in  the  earlier  body  of  water  also  flourished  iu 
the  new  one  and  the  forms  are  lacustrine. 

The  asperitic  andesites  of  Mt.  Konocti  are  interesting  because  they 
contain  pyroxene  and  mica,  but  no  hornblende,  which  is  unusual,  and  be- 
cause they  pass  over  into  acid  glasses.  The  asperite  is  often  almost  wholly 
crystalline,  though  it  has  been  subjected  to  substantially  the  same  physical 
conditions  as  the  glass,  and  the  latter  has  remained  vitreous  because  of  its 
divergent  chemical  composition.  The  mountain  nearly  coincides  in  form 
with  the  theoretical  shape  of  a  volcanic  cone  and  its  highest  point  is  2,936 
feet  above  the  lake  at  high  water.  The  lake  is  1,310  feet  above  sea-level. 

Much  later  than  the  andesite  came  basalt  eruptions,  which  extended  to 
modern  times.  A  part  of  this  rock  also  is  glassy.  All  the  springs  which 
now  issue  at  a  high  temperature  are  probably  due  to  the  basalt  eruptions, 
and  the  borax,  sulphur,  and  cinnabar  are  referable  to  the  same  source. 


SUMMARY.  463 

X  sulphur  Bank. — The  general  geology  of  the  Sulphur  Bank  is  indicated  in 
the  notes  on  Clear  Lake.  The  bank  itself  is  a  small  basalt  area,  through 
which  hot  solfataric  springs  reach  the  surface,  owing  their  heat  to  the  vol- 
canic action  of  which  the  lava  eruption  wa.s  an  earlier  manifestation.  The 
springs  contain  much  sulphydric  acid,  which,  oxidizing  more  or  less  fully  at 
and  near  the  surface,  lias  yielded  native  sulphur  and  sulphuric  acid.  The 
latter  lias  attacked  the  basalt  in  part,  extracting  the  basis  and  leaving  a  mass 
of  more  or  less  pure  silica,  in  which  rounded  nodules  of  undecomposed  rock 
remain.  The  rounded  form  of  these  nuclei  is  certainly  due  to  the  more 
rapid  corrosion  of  the  edges  and  corners  of  the  basalt  blocks,  not  to  any 
structural  peculiarity  of  the  rock.  The  lava  is  bleached  to  an  average 
depth  of  about  twenty  feet. 

In  the  lower  portion  of  the  decomposed  layer  of  rock  the  sulphur  is 
mixed  with  cinnabar.  Near  the  bottom  of  this  rock  layer  the  sulphur  dis- 
appears and  the  ore  is  richer,  while  the  most  extensive  bodies  are  found  at 
depths  beyond  the  limits  of  the  action  of  acid.  The  ores  at  one  portion  of 
the  ground  continued  down  for  several  hundred  feet  into  the  underlying 
recent  lake  beds  and  the  metamorphic  sandstones.  Quartz,  chalcedony, 
calcite,  pyrite,  and  marcasite  are  the  usual  gangue  minerals,  but  many  other 
minerals  are  found  in  small  quantities.  The  marcasite  contains  minute  quan- 
tities of  gold  and  copper.  Bituminous  matter  is  widely  disseminated.  The 
ore  has  been  deposited  exclusively  in  cavities,  and  not  by  substitution.  The 
ore  of  the  lower  workings  is  exactly  like  that  of  most  other  quicksilver  mines. 

The  gases  escaping  from  the  waters  are  carbon  dioxide,  hydrogen 
sulphide,  sulphur  dioxide,  and  marsh  gas.  The  waters  contain  chiefly  car- 
bonates, borates,  and  chlorides  of  sodium,  potassium,  and  ammonium ;  but 
alkaline  sulphides  are  also  present.  At  the  ordinary  pressure  the  water 
does  not  dissolve  cinnabar,  on  account  of  the  presence  of  ammonia,  but  I 
have  proved  that  at  somewhat  higher  pressures  it  would  effect  solution.  It 
is  beyond  question  that  the  cinnabar  has  been  deposited  from  waters  of 
almost  exactly  the  same  composition  as  those  now  issuing  from  the  mine 
and  that  the  formation  of  ore  is  still  in  progress.  Deposition  of  the  ore 
seems  to  have  been  effected  chiefly  by  relief  of  temperature  and  pressure 
in  the  presence  of  ammonia,  not  by  acidification  of  the  solutions. 


4G4  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPIS. 

Very  large  quantities  of  quicksilver  have  been  taken  from  this  prop- 
erty, but  it  lias  not  been  worked  with  system  and  has  been  insufficiently 
prospected  below  the  basalt.  There  is  no  reason  to  suppose,  however,  that 
it  is  nearly  exhausted. 

Close  to  Borax  Lake  lies  a  very  interesting  area  of  glassy  basalts, 
ranging  all  the  way  from  a  nearly  normal  olivinitic  rock  to  a  pure  glass. 
As  is  the  case  with  the  andesites  across  the  lake,  the  glass  is  very  acid  and 
contains  little  lime,  but  much  alkali. 

Borax  Lake  is  a  shallow  pond,  without  an  outlet,  into  which  springs 
similar  to  those  now  flowing  from  Sulphur  Bank  once  drained.  These 
springs  came  from  the  obsidian  area,  and  to  them  the  borax  contents  of  the 
lake  is  due.  They  issued  at  the  point  called  Little  Sulphur  Bank,  which 
is  still  hot  and  moist  and  shows  native  sulphur.  It  is  stated  on  excellent 
authority  that  cinnabar  in  small  quantities  was  found  here.  Maggots  of 
Ephydra  calif  arnica  and  of  a  species  of  Strat'tomy*  live  in  the  lake. 

The  Knoxviiie  district. —  The  region  about  Knoxville  consists  of  metamor- 
phosed and  unaltered  rocks  of  Neocomian  age,  through  which  a  small  basalt 
eruption  has  broken,  and  contains  a  number  of  quicksilver  mines  and  pros- 
pects. I  know  of  no  other  district  so  favorable  as  this  for  the  determina- 
tion of  the  age  of  the  metamorphie  rocks  .and  for  a  study  of  their  character, 
excepting  Mt.  Diablo.  Rocks  occur  in  all  stages  of  metamorphism,  and 
the  transitions,  together  with  the  structural  relations,  show  that  even  the 
serpentine  is  not  of  eruptive  origin.  The  metamorphosed  and  unaltered 
rocks  are  also  so  related  as  to  preclude  the  supposition  that  the  former  are 
crystalline  sediments.  One  side  of  an  eroded  anticlinal  is  metamorphosed, 
while  the  other  is  unchanged  and  fossiliferous.  Fossiliferous  strata  in  a 
nearly  vertical  position  pass  over  into  metamorphic  rocks  in  the  direction 
of  their  strike,  and  patches  of  unchanged  rocks  remain  in  metamorphosed 
masses.  The  fossils  of  the  unaltered  strata  are  of  Neocomian  age  and  the 
principal  species  are  Amelia  concentrica  and  A.  int>*<[nr>iKis.  The  series  carry- 
ing these  shells  are  called  the  Knoxville  group  from  the  name  of  this  locality. 

Excellent  opportunities  are  here  afforded  for  studying  the  passage  of 
sandstone  into  pseudodiabase  and  pseudodiorite  and  the  alteration  of  these 
rocks  to  serpentine.  The  direct  change  of  slightly  altered  sandstones  to 


SUMMARY. 

serpentine  may  also  be  seen  in  a  very  striking  manner.  Serpentinization 
takes  place  from  cracks  in  the  sandstone  just  as  it  does  in  olivines,  excepting 
for  the  difference  of  scale.  The  meshes  of  the  net  in  sandstone  croppings 
are  often  about  a  foot  across,  while  those  in  olivine  are  microscopic. 

The  ore  deposits  occur  at  half  a  dozen  points  in  the  district,  all  of 
them  near  the  basalt  area,  which  is  as  nearly  as  possible  in  the  center  of 
the  group  of  ore  bodies.  Ore  is  stated  on  good  authority  to  have  been 
found  also  in  the  Lake  claim,  at  the  contact  of  a  basalt  dike  with  the  in- 
closing metamorphic  rocks.  Many  mineral  springs  exist  around  the  basalt 
area  close  to  the  mines  and  some  of  them  carry  borax.  Solfataric  gases 
still  issue  in  small  quantities  at  one  point  in  the  Redington  mine  and  the 
upper  portions  of  the  ore  deposits  are  of  such  a  character  as  to  indicate 
that  they  were  deposited  near  an  original  surface.  All  of  these  facts  indi: 
cate  that  the  deposits  are  indirectly  due  to  the  basalt  eruption  and  that  the 
nature  of  the  process  was  similar  to  that  at  Sulphur  Bank. 

The  upper  part  of  the  famous  Redington  mine  was  an  extremely  rich 
bonanza  of  great  size  and  irregular  form.  It  carried  much  metacinnaba- 
rite.  Leading  up  to  this  mass  from  below  were  three  regular  fissures,  and 
two  of  them  were  filled  with  ore,  forming  well  defined  fissure  veins.  This 
is  particularly  interesting  as  a  proof  that  true,  simple  fissure  veins  maybe 
formed  by  hot  solfataric  springs,  which  has  been  doubted  by  some  geol- 
ogists. 

The  California  or  Reed  mine,  the  Manhattan,  the  Lake,  the  Andalusia, 
and  several  prospects,  as  well  as  the  Redington,  lie  in  this  district,  but  of 
late  years  only  the  last  has  been  worked.  Metacinnabarite  was  the  princi- 
pal ore  of  the  California  Stibnite  occurs  on  the  Lake  and  Manhattan 
claims  and  is  said  to  have  been  found  in  contact  with  cinnabar. 

New  idria. — The  New  Idria  mining  district  lies  among  some  of  the  highest 
peaks  of  the  Coast  Ranges,  at  the  southern  end  of  the  Mt.  Diablo  Range. 
The  views  are  very  extensive  and  the  scenery  is  picturesque,  but  it  is  in  part 
very  forbidding,  the  portion  of  the  Coast  Ranges  lying  to  the  northeast  of 
the  district  being  a  mountainous  desert. 

The  higher  portion  of  the  Mt.  Diablo  Range  is  here,  as  for  the  greater 
part  of  its  length,  composed  of  highly  metamorphosed  -rocks  of  the  Knox- 

MON  xm— —30 


466  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

ville  series.  No  fossils  are  known  to  occur  in  it  here,  but  at  the  northern 
end  of  the  range  they  are  abundant,  and  they  are  found  again  at  San  Luis 
Obispo,  to  the  south,  in  precisely  similar  rocks. 

On  the  northeastern  flank  of  the  range  lie  the  rocks  of  the  Chico -Tejon 
series.  These  are  tilted  at  angles  averaging  about  45°,  but  are  only  slightly 
flexed.  The  lower  part  of  the  series  lies  unconformably  upon  the  meta- 
morphic  beds,  as  is  proved  by  the  structure  and  by  the  presence  of  meta- 
morphic  pebbles  in  Chico  conglomerates. 

The  Chico  and  Tejon  are  absolutely  conformable  at  New  Idria  and 
sedimentation  went  on  continuously  from  one  period  to  the  other.  Fossils 
are  not  numerous,  but  are  present  in  sufficient  number  fully  to  identify  the 
age  of  the  rocks.  Both  portions  of  the  series  show  many  of  the  concre- 
tions mentioned  above  as  due  to  induration  by  decomposing  organic  matter. 
The  Tejon  beds  contain  coal  seams  which  were  exploited  on  a  small  scale 
for  many  years. 

No  lava  exists  in  the  district,  but  there  is  a  considerable  area  of  basalt 
just  north  of  Vallecitos  Caflon,  about  ten  miles  from  the  mine.  There  are 
cold  sulphur  springs,  but  no  hot  ones. 

Next  to  the  New  Almaden,  the  New  Idria  has  been  much  the  most  pro- 
ductive quicksilver  'mine  in  North  America.  The  ore  contains  the  usual 
mixture  of  cinnabar,  pyrite,  and  quartz,  accompanied  by  some  bitumen  ; 
metacinnabarite  also  was  found  in  the  New  Hope  lode  in  very  large  quan- 
tities and  in  less  abundance  at  another  point  in  the  mine.  The  structure  is 
extremely  complex,  but  typically  developed  stockworks,  veins,  and  impreg- 
nations all  occur.  Faults  and  cross-courses  make  successful  explorations 
very  difficult  and  uncertain. 

The  ore  is  almost  entirely  deposited  in  Neocomian  rocks,  but  to  a  small 
extent  also  in  the  Chico  beds.  The  deposition  has  taken  place  since  the 
Post-Miocene  upheaval  and  is  seemingly  referable  to  about  the  same  period 
as  the  other  deposits.  The  analogies  point  to  the  action  of  hot  springs,  but 
there  is  no  direct  proof  that  the  solutions  were  of  high  temperature. 

The  San  Ciirlos,  Aurora,  Picacho,  and  other  mines  which  have  yielded 
small  quantities  of  ore  lie  at  no  great  distance.  In  all  of  them  the  ore  has 
been  deposited  in  shattered  rock  masses  of  the  metamorphic  series.  No- 


SUMMARY.  467 

where  in  this  region  is  there  any  evidence  of  the  substitution  of  ore  for 
rock.  ,  -*T 

New  Aimaden  district. — The  first  discovered  and  the  most  productive  of  the 
quicksilver  mines  of  North  America  is  the  New  Aimaden,  and  in  the  same 
district  the  Guadalupe,  Enriquita,  and  other  mines  have  yielded  quicksilver. 
The  district  is  well  watered  and  wooded  and  is  more  attractive  than  any 
other  of  the  quicksilver  camps. 

Upon  highly  metamorphosed  rocks  lie  Miocene  sandstones,  which  were 
sharply  folded  at  the  Post-Miocene  upheaval.  They  are  not  conformable 
with  the  lower  series  and  contain  pebbles  from  these  older  beds.  In  the 
older  rocks  near  New  Aimaden  Mr.  Gabb  found  Aucella,  proving  the  pres- 
ence of  the  Knoxville  series. 

In  this  district  is  the  only  mass  of  rhyolite  thus  far  found  in  the  Coast 
Ranges.  It  forms  a  dike  nearly  parallel  to  the  line  connecting  the  New 
Aimaden  and  the  Guadalupe.  It  is  almost  continuous,  and  I  have  followed 
it  for  a  distance  of  several  miles.  It  is  certainly  Post-Miocene  and  prob- 
ably Post-Pliocene. 

The  New  Aimaden  is  a  very  extensive  mine,  said  to  contain  as  much 
as  40  miles  of  galleries.  Much  of  this  length  is  open,  and  admirable  op- 
portunities are  afforded  for  study  of  the  ore  and  structure.  The  ore  is 
cinnabar,  with  occasional  traces  of  native  quicksilver,  accompanied  by 
pyrite  and  marcasite,  with  rare  crystals  of  chalcopyrite.  The  gangue  is 
quartz,  calcitc,  dolomite,  and  magnesite.  These  materials  are  deposited  in 
shattered  masses  of  pseudodiabase,  pseudodiorite,  serpentine,  and  sand- 
stone. There  is  no  deposition  by  substitution  and  impregnations  are  very 
subordinate.  Considered  in  detail,  the  ore  bodies  are  stock  works ;  but 
they  are  arranged  along  definite  fissures  and  the  deposits  as  a  whole  have 
a  vein-like  character  and  answer  to  the  "  chambered  veins  "  defined  in  a 
subsequent  paragraph.  The  workings  have  developed  two  main  fissures. 
One  of  these  dips  from  the  surface  at  a  high  angle  and  in  a  nearly  straight 
line.  The  other  strikes  in  nearly  the  same  direction  as  the  first,  dips 
steeply  from  the  surface,  then  flattens  and  approaches  the  first  fissure  rap- 
idly, again  becomes  very  steep,  and  in  the  lowest  workings  almost  coincides 
with  the  first.  In  vertical  cross-section  the  two  fissures  form  a  figure 


468  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

resembling1  a  V.  The  great  ore  bodies  are  distributed  along  these  two 
fissures,  making  irregularly  into  the  walls.  The  wedge  between  the  fissures 
also  contains  ore  bodies.  They  are  always  accompanied  by  evidences  of 
motion  and  by  a  mass  of  attrition  products  of  various  rocks — clay  in  a 
mining  but  not  in  a  mineralogical  sense.  This  clay  is  usually  on  the 
hanging  wall  and  is  called  alia. 

The  other  mines  of  the  district  contained  similar  ores  in  similar  rocks. 
The  Gtiadalupe  was  the  most  productive,  but  was  not  at  work  and  was  full 
of  water  during  my  visit. 

All  the  deposits  of  the  district  appear  to  occur  along  a  rather  simple 
fissure  system.  The  main  fissure  is  nearly  parallel  to  the  rhyolite  dike  at 
the  Guadalupe.  It  follows  the  direction  of  the  hills,  the  axis  of  which  curves 
gradually  away  from  the  dike  for  a  certain  distance.  Passing  through  or 
near  the  San  Antonio  and  Enriquita,  it  seems  to  break  across  the  ridge  at 
the  America  and  enters  the  Almaden  on  the  strike  of  its  two  great  fissures. 
It  is  near  this  fissure  that  new  ore  bodies  are  most  likely  to  be  found.  The 
Washington  seems  to  be  on  a  branch  of  the  main  fissure. 

This  fissure  was  probably  formed  at  the  time  of  the  rhyolite  eruption, 
to  which  also  I  ascribe  the  genesis  of  the  ore. 

steamboat  springs. — This  curious  thermal  area  lies  just  within  the  desert 
Great  Basin,  in  full  sight  of  the  forests  and  snows  of  the  Sierra  Nevada. 
It  is  only  six  miles  in  a  straight  line  from  the  (Jomstock  lode. 

Granite  underlies  the  district  and  much  of  the  area  exposed  is  of  this 
rock.  Upon  it  lie  metamorphosed  rocks  of  the  Jura-Trias  series  and  lavas. 
Older  andesites  and  younger  asperites,  described  in  a  former  paragraph, 
cover  a  large  space,  and  there  is  a  considerable  area  of  basalt,  which  repre- 
sents the  last  eruption. 

The  springs  are  numerous  and  some  of  them  reach  the  boiling-point. 
They  are  unquestionably  of  volcanic  origin  and  due  to  the  basalt  eruption. 
They  reach  the  surface  in  the  granite  area.  The  flowing  springs  are  con- 
fined at  present  to  a  small  group  of  fissures,  but  steam  in  small  quantities 
issues  at  many  points  in  the  region  marked  by  evidences  of  solfataric  action, 
and  this  region  is  substantially  a  continuous  one.  In  some  portions  of  it 
the  sinters  arc  clralcedony,  in  others  they  consist  to  a  considerable  extent 


SUMMARY.  469 

of  carbonates,  and  in  one  portion  (at  the  mine)  the  deposits  of  sinter  are 
insignificant  in  extent,  the  chief  effect  having  been  decomposition  of  granite 
and  the  precipitation  of  sulphur  and  cinnabar.  In  this  part  of  the  area  also 
steam  and  gas  still  issue  in  small  quantities. 

The  amount  of  cinnabar  is  considerable.  The  ore  was  mined  and 
reduced  a  few  years  since,  but  mining  would  not  pay  at  present  prices. 

Quicksilver  in  very  small  amounts  is  being  deposited  by  the  springs 
now  active,  together  with  gold  and  several  other  metals.  They  are  dis- 
solved as  alkaline  sulphosalts,  as  will  be  explained  in  a  subsequent  para- 
graph. The  waters  and  gases  are  similar  to  those  of  Sulphur  Bank,  except- 
ing that  ammonia  and  organic  compounds  are  absent. 

The  four  metals  most  abundant  in  the  present  spring  deposits,  anti- 
mony, arsenic,  lead,  and  copper,  exist  in  the  granite,  but  I  was  unable  to 
detect  quicksilver.  This  may  be  due  to  the  small  quantity  of  quicksilver 
in  the  average  granite  or,  as  I  think  more  probable,  to  irregularity  in  the 
composition  of  that  rock.  The  granite  is  the  probable  source  of  the  mercury. 

The  Oathill,  Great  Eastern,  and  Great  Western  districts The    neighborhood     of    Oathill 

is  a  most  interesting  one  and  contains  many  quicksilver  deposits  within  a 
small  area.  The  underlying  rock  is  of  the  Knoxville  series,  identified  by 
the  presence  of  Aucdla.  It  is  in  part  metamorphosed  and  serpentinized  and 
in  part  unaltered.  Andesite  and  basalt  have  broken  through  it. 

The  basalt  eruption  gave  rise  to  hot  springs,  one  of  which  still  ex- 
ists at  Lidell,  issuing  from  the  workings  of  a  now  abandoned  quicksilver 
mine.  In  two  cases  also  cinnabar  deposits  occur  at  the  contact  between 
basalt  dikes  and  the  adjoining  rock,  forming  veins.  Irregular  stockworks 
of  the  more  usual  type  also  occur. 

The  Oathill  mine  is  the  principal  one  of  the  mines  belonging  to  the 
Napa  Consolidated  Company.  It  is  in  unaltered  sandstone,  the  strata  of 
which  are  nearly  horizontal.  The  deposits  are  true  veins,  cutting  the  strata 
at  an  angle  of  45°.  From  these  veins  ore  bodies  sometimes  make  out  into 
the  country,  following  the  stratification.  These  are  impregnations.  The 
ore  is  the  usual  mixture  of  cinnabar,  pyrite,  silica,  and  calcite,  and  bitumen 
also  occurs.  Small  quantities  of  barite  are  also  found,  and  this  is  the  only 
case  in  which  this  mineral  is  known  to  accompany  cinnabar  in  California. 
It  is  also  found  at  Almaden, 


470  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  Great  Western  lies  near  the  extinct  andesitic  volcano  called  Mt. 
St.  Helena.  The  country  rock  is  of  the  metamorphic  series,  and  both  ande- 
site  and  basalt  have  broken  through  it,  A  layer  of  opalized  serpentine 
accompanies  the  ore-bearing  ground.  The  ore  is  chiefly  cinnabar,  but  at 
one  point  rock  impregnated  with  native  mercury  was  found.  The  cinnabar 
was  deposited  simultaneously  with  pyrite  and  quartz.  The  bitumen  posep- 
nyte  was  first  described  from  this  mine.  The  deposit  consists  of  a  tabular, 
reticulated  mass  connected  with  a  fissure  system  and  it  lies  at  the  contact 
between  serpentine  and  nearly  unaltered  sandstone.  If  it  does  not  come 
under  the  common  definition  of  a  vein,  it  is  closely  related  to  that  class  of  ore 
bodies. 

The  Great  Eastern  lies  in  Sonoma  County,  far  from  other  quicksilver 
deposits  and  six  miles  from  lava.  The  rock  is  the  ordinary  metamorphosed 
material  of  the  Coast  Ranges  The  ore  occurs  in  black,  opalized  serpentine, 
which  here  forms  a  definite  ledge.  The  ore  seems,  as  usual,  to  be  of  some- 
what later  date  than  the  formation  of  opal  and  is  accompanied  by  pyrite, 
quartz,  and  bitumen.  The  ore  seems  to  form  a  pipe,  which  is  continuous 
from  the  surface  to  a  depth  of  450  feet.  This  pipe  I  believe  to  lie  on  a 
continuous  fissure. 

All  of  the  above  mines  have  produced  important  quantities  of  quick- 
silver. 

other  quicksilver  deposits —  So  far  as  I  know,  the  most  northerly  cinnabar 
deposits  on  the  west  coast  south  of  British  Columbia  are  in  Douglas  County, 
Oregon.  In  the  northern  part  of  Trinity  County,  California,  there  is  also  a 
mine.  These  widely,  separated  deposits  both  lie  on  the  northerly  continua- 
tion of  the  middle  Coast  Ranges,  where  most  of  the  deposits  occur.  From 
Clear  Lake  to  Santa  Barbara,  as  is  shown  on  the  map  of  California  accom- 
panying this  report,  the  deposits  are  thickly  scattered. 

Of  the  very  many  deposits  briefly  described  in  Chapter  XIII,  only  a 
few  can  be  mentioned  here.  The  Manzanita  mine,  Colusa  County,  is  very 
remarkable  for  the  association  with  cinnabar  of  free  gold,  often  in  feathery 
crystals.  Pyrite  accompanies  the  ore  and  the  gangue  is  chiefly  quartz.  There 
is  free  sulphur  also,  as  well  as  other  evidence  that  the  ore  was  deposited 
by  hot  sulphur  springs,  such  as  still  issue  within  a  few  hundred  feet  of  the 


SUMMARY.  471 

mine.  There  is  no  lava  in  the  neighborhood.  In  the  Stayton  mines,  San 
iienito  County,  large  quantities  of  stibnite  were  associated  with  cinnabar. 
The  Oceanic,  in  San  .Luis  Obispo  County,  is  in  unaltered  sandstone,  sup- 
posed to  be  Miocene.  Most  of  the  other  -deposits  occur  in  shattered  rock 
masses  of  the  Knoxville  group,  forming  stockworks.  In  some  cases  they 
seem  to  be  accompanied  by  true  veins,  and  sufficient  exploration  would 
doubtless  show  a  fissure  system  connected  with  each  of  them.  The  usual 
mineral  association  is  the  same  so  often  described  above. 

On  the  gold  belt  of  California  cinnabar  occurs  in  pebbles,  in  aurifer- 
ous gravels,  and  in  true  gold  quartz  veins,  so  that  there  are  mercuriferous 
gold  veins  as  well  as  auriferous  deposits  of  cinnabar.  In  the  Barcelona  sil- 
ver mine,  Belmont,  Nev.,  cinnabar  was  found  with  silver  ore  in  the  vein. 
Cinnabar  also  occurs  in  a  silver  vein  near  Calistoga,  Cal.  In  Idaho  float 
cinnabar  has  several  times  been  found,  in  some  cases  with  a  calcite  matrix. 
A  statement  repeatedly  made  in  the  literature  reads  as  if  this  ore  had  been 
found  in  place  in  Idaho,  but  this  is  not  the  case.  In  Utah,  near  Marysville, 
a  deposit  of  the  selenide  of  mercury,  tiemannite,  was  being  mined  and  re- 
duced early  in  1887.  So  far  as  I  know  this  is  the  only  case  in  which  this 
mineral  has  been  found  in  sufficient  quantities  to  form  the  basis  of  commer- 
cial exploitation.  None  of  the  other  deposits  requires  special  mention  in 
this  abstract. 

Discussion  of  the  ore  deposits. —  The  general  results  of  the  observations  on  the 
various  mines  are  discussed  in  Chapter  XIV.  Microscopical  examination  of 
the  ores  shows  that  cinnabar  is  usually  deposited  in  immediate  contact  with 
quartz,  and  that,  though  opal  and  chalcedony  are  frequently  found  very 
near  the  particles  of  cinnabar,  there  is  seldom,  if  ever,  actual  contact.  More 
rarely  the  cinnabar  is  directly  embedded  in  calcite.  The  evidence  of  the 
microscope  also  goes  to  prove  that  the  ore  is  always  deposited  in  fissures  in 
in  dense  rocks  or  in  the  interstitial  spaces  of  porous  sandstones.  Macro- 
scopically  the  same  conclusion  had  been  reached.  The  assertion  often 
made  that  cinnabar  has  been  deposited  by  substitution  for  wall  rock  at 
Almaden  in  Spain  is  certainly  incorrect,  and,  in  my  opinion,  no  such  case  has 
been  adequately  proved  to  exist.  The  only  substance,  excepting  metallic 
sulphides,  which  cinnabar  is  known  to  replace  is  organic  matter,  and  this 
seems  to  be  very  exceptional 


472  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

The  usual  mineral  association  consists  of  cinnabar  and  traces  of  native 
mercury,  with  pyrite  and  marcasite,  silica  and  carbonates  ;  but  sulphur 
occurs  at  three  mines,  chalcopyrite  is  not  very  uncommon,  stibnite  is  found 
(though  rarely),  gold  or  auriferous  pyrite  occurs  in  a  few  cases,  millerite  in  a 
number  of  instances,  and  barite  in  one.  These  substances  and  their  decom- 
position-products are  rare.  Excepting  in  Steamboat  Springs,  at  Calistoga, 
and  in  the  Barcelona  mine,  I  do  not  know  of  silver,  lead,  or  zinc  minerals 
accompanying  cinnabar  in  the  western  United  States.  A  new  bitumen,  two 
new  chromium  minerals,  and  a  red  antimony  sulphide  have  been  detected 
with  cinnabar  in  this  investigation. 

The  great  similarity  of  the  deposits  points  to  a  common  history  for 
them  all.  The  evidence  is  strong  in  many  cases  that  they  have  been 
deposited  from  hot  sulphur  springs  and  the  remainder  have  probably  been 
produced  in  the  same  way.  The  inclosing  rock*  have  been  without  effect 
upon  the  deposits,  for  nearly  all  the  rocks  in  the  Coast  Ranges  inclose  ore 
bodies.  These  facts  point  to  a  common,  deep-seated  origin. 

It  has  often  been  asserted  that  quicksilver  ores  do  not  form  deposits 
similar  to  those  of  the  ores  of  other  metals,  but  I  can  find  no  evidence  of 
this  Stockworks,  impregnations,  and  regular  veins  all  occur,  and  no  other 
or  peculiar  form  of  deposit  is  known  to  me.  Many  of  the  discussions  as  to 
whether  or  not  deposits  are  veins  depend  on  the  various  uses  of  this  word. 
To  miners  it  usually  means  deposits  along,  or  directly  connected  with,  a 
distinct  fissure  ;  to  a  geologist  a  vein  means  a  deposit  between  well  defined, 
nearly  parallel  walls  which  have  once  been  in  contact.  Irregular  bodies  of 
ore,  even  those  connected  with  distinct  fissures,  are  known  to  him  as  stocks, 
stockworks,  or  by  some  similar  name.  I  propose  to  call  the  contents  of  dis- 
tinct fissures  with  very  irregular  walls  chambered  veins  and  the  irregular 
openings  or  ore  bodies  connected  with  a  main  fissure  vein  chambers.  A 
chambered  vein  may  then  be  defined  as  a  deposit  consisting  of  an  ore- 
bearing  fissure  and  ot  ore  bodies  contiguous  with  the  fissure,  but  extending 
into  the  country  rock.  The  greater  part  of  the  cinnabar  deposits  would 
come  under  this  definition,  which  would  also  apply  to  many  deposits  of 
other  ores.  If  this  term  were  adopted,  simple  fissure  vein  would  still 
describe  the  form  of  deposits  now  known  to  mining  geologists  as  veins. 


SUMMARY.  473 

Solution  and  precipitation  of  cinnabar  and  other  ores. TllC   Wcltei'S  of  Steamboat   Springs 

are  now  depositing  gold,  probably  in  the  metallic  state;  sulphides  of  arsenic, 
antimony,  and  mercury ;  sulphides  or  sulphosalts  of  silver,  lead,  copper, 
and  zinc;  iron  oxide  and  possibly  also  iron  sulphides;  and  manganese,  nickel, 
and  cobalt  compounds,  with  a  variety  of  earthy  minerals.  The  sulphides 
which  are  most  abundant  in  the  deposits  are  found  in  solution  in  the  water 
itself,  while  the  remaining  metallic  compounds  occur  in  deposits  from 
springs  now  active  or  which  have  been  active  within  a  few  years.  These 
springs  are  thus  actually  adding  to  the  ore  deposit  of  the  locality,  which 
has  been  worked  for  quicksilver  in  former  years  and  would  again  be  ex- 
ploited were  the  price  of  this  metal  to  return  to  the  figure  at  which  it  stood 
a  few  years  since.  At  Sulphur  Bank  ore  deposition  is  still  in  progress. 
The  waters  of  the  two  localities  are  closely  analogous.  Both  contain  sodium 
carbonate,  sodium  chloride,  sulphur  in  one  or  more  forms,  and  borax  as 
principal  constituents,  and  both  are  extremely  hot,  those  at  Steamboat 
Springs  in  some  cases  reaching  the  boiling-point.  In  attempting  to  deter- 
mine in  what  forms  the  ores  enumerated  can  be  held  in  solution  in  such 
waters,  it  is  manifestly  expedient  to  begin  by  studying  the  simplest  possi- 
ble solutions  of  the  sulphides,  and  particularly  of  cinnabar. 

The  statements  in  the  previous  literature  of  this  subject  are  incomplete 
and  in  part  discordant,  so  that  the  subject  required  reinvestigation,  particu- 
larly as  to  the  sodic  solvents.  It  was  found  that,  provided  a  small  quantity 
of  sodic  hydrate  be  present,  one  molecule  of  mercuric  sulphide  unites  with 
two  molecules  of  sodic  sulphide  to  form  a  freely  soluble  sulphosalt  and  that 
an  excess  of  sodic  hydrate  is  without  effect  upon  the  solubility.  Even  when 
sodic  hydrate  is  entirely  absent,  mercuric  sulphide  is  freely  soluble  in  aque- 
ous solutions  of  sodic  sulphide,  though  the  contrary  has  repeatedly  been 
asserted;  but  either  one  molecule  of  mercuric  sulphide  then  unites  with 
three  of  sodic  sulphide,  instead  of  two,  or  a  mixture  of  sulphosalts  nearly 
corresponding  to  this  compound  is  formed. 

Sodic  sulphydrate  when  cold  is  absolutely  without  effect  upon  mercuric 
sulphide,  but  when  the  mixture  is  heated  on  the  water-bath  the  sulphydrate 
is  decomposed  and  sodic  sulphide  is  formed;  it  unites  with  the  mercuric  sul- 
phide in  the  proportion  of  four  molecules  of  the  former  to  one  of  the  latter. 
A  perfectly  limpid  solution  results.  The  same  compound  is  produced  when 


474  QUICKSILVER  DEPOSITS  OF  THE  PACIFIC  SLOPE. 

mixtures  oi'  sodic  sulphide  and  sodic  sulpliydrate  are  brought  in  contact  with 
mercuric  sulphide.  The  presence  of  sodic  carbonates  diminishes  the  solu- 
bility of  mercuric  sulphide,  but  does  not  prevent  solution.  Ammonium 
carbonate  completely  prevents  solution  at  temperatures  below  the  boiling- 
point,  but  not  at  14*)°  C. 

These  facts  suffice  to  lead  to  important  conclusions  with  reference 
to  spring  waters,  such  as  those  mentioned  above.  When  neutral  sodic 
carbonate  is  treated  with  sulphydric  acid  at  ordinary  temperatures,  sodic 
sulpliydrate  forms.  At  temperatures  approaching  the  boiling-point,  it  is 
probable  that  a  certain  quantity  of  sodic  sulphide  is  also  produced.  At 
these  higher  temperatures  either  of  these  sulphur  compounds  will  dissolve 
cinnabar,  and  the  presence  of  sodic  carbonates  will  not  prevent  solution. 
These  conclusions  were  amply  verified  by  direct  experiments. 

Mercuric  sulphide  may  be  wholly  or  partly  precipitated  from  solutions 
of  the  sulphosalts  in  many  ways:  by  excess  of  sulphydric  acid  or  of  other 
acids,  by  borax  and  other  mineral  salts,  by  cooling  (especially  in  the  presence 
of  ammonia),  and  by  dilution.  In  the  last  case  a  certain  quantity  of  metallic 
quicksilver,  as  well  as  mercuric  sulphide,  is  formed,  and  this  is  very  probably 
one  of  the  methods  by  which  native  quicksilver  has  been  produced  in  nature. 

Metallic  gold,  iron  pyrites,  cupric  sulphide,  and  zincblende  we.re  found 
to  be  soluble  in  solutions  of  sodic  sulphide  and  in  solutions  of  the  carbonates 
to  which  sulphydric  acid  had  been  added.  All  of  them  appear  to  form 
sulphosalts  with  the  alkaline  compound.  It  has  long  been  known  that 
sulphides  of  arsenic  and  antimony  are  soluble  in  sodic  sulphide.  They 
also  dissolve  in  mixtures  of  the  carbonates  and  sulphides  of  sodium. 

Natural  solutions  of  sodic  carbonates  and  sulphides,  which  are  common 
components  of  hot  spring  waters,  are  thus  capable  of  dissolving  at  least  five 
of  the  principal  metals,  as  well  as  sulphur,  arsenic,  and  antimony.  Combi- 
nations of  these  elements  form  a  large  part  of  the  minerals  found  in  mines. 
There  is  little  or  no  doubt  that  the  cinnabar  of  the  California  deposits  has 
been  dissolved  and  precipitated  as  indicated  above  and  that  at  least  a  part, 
of  the  gold  of  that  State  has  been  produced  in  a  similar  manner,  but  I  by  no 
means  assert  that  natural  deposits  of  cinnabar  and  of  gold  have  never  been 
produced  in  any  other  way. 


SUMMARY.  475 

origin  of  the  ore. —  There  is  tli  o  strongest  evidence  for  the  supposition  that 
the  cinnabar,  pyrite,  and  gold  of  the  quicksilver  mines  of  the  Pacific  slope 
reached  their  present  positions  in  hot  solutions  of  double  sulphides.  Either 
the  metals  must  have  been  leached  fronrtlre  granite  or  they  were  derived  from 
an  infragranitic  source,  for  examination  of  the  conditions  of  occurrence  shows 
it  utterly  improbable  that  they  were  extracted  from  any  volcanic  rock  at  or 
near  the  surface,  while  the  sedimentary  strata  of  the  region  are  composed 
of  granitic  detritus.  No  one  fact  or  locality  absolutely  demonstrates  whether 
the  metals  were  originally  components  of  the  granite  or  came  from  beneath 
it,  but  the  tendency  of  the  evidence  at  all  points  is  to  the  supposition  that 
the  granite  yielded  the  metals  to  solvents  produced  by  volcanic  agencies, 
and  when  all  the  evidence  is  considered  together  it  is  found  that  this 
hypothesis  explains  all  the  known  circumstances  very  simply,  while  the 
supposition  of  an  infragranitic  origin  leads  to  numerous  difficulties.  Though 
no  one  of  these  may  be  in  itself  inexplicable,  when  taken  as  a  whole  they 
appear  to  me  to  be  so.  Had  solutions  of  quicksilver  been  formed  in  com- 
pany with  other  products  at  the  foci  of  volcanic  activity,  cinnabar  would 
often  be  met  with  in  craters.  Though  it  is  often  found  associated  with 
volcanic  effects,  it  perhaps  never  occurs  in  craters.  Were  the  solutions 
formed  below  the  granite,  ore  deposition  would  also  almost  certainly  take 
place  in  part  within  the  granite,  and  most  ore  deposits  would  continue 
down  into  that  rock,  probably  growing  richer  with  increasing  depth.  On 
the  other  hand,  the  distribution  of  the  deposits  relatively  to  volcanic  vents 
is  such  as  would  be  anticipated  if  the  ore  were  known  to  be  leached  from 
the  granite  by  hot  waters  of  volcanic  origin.  The  varying  richness  of  the 
different  deposits  also  corresponds  to  the  irregularity  in  the  composition  of 
the  granite  and  in  the  extent  of  surface  exposed  along  the  underground 
passages  through  which  the  waters  must  have  reached  the  surface.  I  Finally, 
at  Steamboat  Springs,  at  least,  the  composition  of  the  granite  answers  to 
that  of  the  deposits  of  springs  which  are  still  depositing  small  quantities  of 
quicksilver.  It  thus  seems  fairly  certain  that  the  quicksilver  and  gold  are 
derived  from  the  granite.  I  entertain  little  doubt  that  many  of  the  gold 
veins  of  California  have  a  similar  origin,  while  others  have  probably  been 
produced  by  the  action  of  cold  surface  waters. 


INDEX. 


Page. 

Abbott's  mine,  Culnsa  County 

Arhiardi,  A.  d1,  cited 5, 15, 35, 47, 43,  £3 

Acton.  K.,  cit.-d *9 

Aden,  Arabia,  ciuuibar  at 44 

^Etna  mines,  Napa  C  nnty 354  371 

Afgbauistou,  cinnabar  in  44 

Africa,  cinnabar  in 43  i 

Age  of  strata  in  Seated  by  resemblances 187  | 

Alaska,  A  ucella  in 201   I 

cinnabar  in   3S4,  385 

Aleutian  I  lands,  Aucttta  in 20-   | 

Algeria  cinnabar  in  43 

Alkaline  sulphides,  action  of,  <  n  cinua'  ar 419 

Alanite 119  ! 

Al  i  aden,  Spain,  cinnabar  deposits  at 390 

description  of xvi  28 

historical  notes  ou ^  ( 

no  substitution  at 399 

Albtat  New  Almaden  3:6 

Altooua  mine,  Trinity  County 36i 

Amalgim,  from  Bri  i<h  Columbia -..  384 

from  heGold  Be't 383 

Amalgamation  proct1  8,  invention  of  .. 4 

quicksilver  consumed  in 3 

America  mine,  Ni  w  Almadeu  district 327 

Amiata,  Monte,  in  Tuscany,  glassy  tr.jchyte  from 159 

Ammonia,  at  Sulphur  liank 259 

erlectof,  ons  luti^ns  of  cinua1.  ar 411 

precipitate*  ciun.ibnr  at  Sulphur  Hank .200,209 

A  niiaman  Islands,  cinnabar  in  the 47 

Audesite,  analysis  of 151 

atflearLake 238 

atGreatWest.su  mine  3-9 

at  Oathill 316 

cinnabar  depos'ts  in '-45,  379 

of  Mayaemas  ills  iict 3  0 

Audesites,  age  of  the. 222 

classification  of  the  119 

of  Steamboat  Springs 116,331 

of  Washoo  district 1 19 

Andesitic  obsidian 153 

analysis  of 151 

Anticlinal,  partially  metamorphosed 27G 

Autigorite  in  nietamorpliic  rocks 113 

Antimony  sulphides,  solubility  of. 434 

Antise!!.  T.  cited 17C 

Aoust,  V.  d',  cited 17,27 

Apatite,  conversion  of,  to  serpentine 124 

occurrence  of,  in  metamorphic  rocks 85 

Araijolite  ;U  Knoxville 286 

Archaean  rocks,  c  mi  pared  with  metarnorphir.s 138,  4.'»8 

in  California  177 

Arcost-  sandstone 61 


Page. 

Argentine  Republic,  cinnabar  in  the 23 

Argcutite,  insolubility  of 434 

Arsenic  sulphides,  solubility  of 434 

Arzruni,  A.,  cited    42,43,44 

Ascension  theory 442 

Asia,  Auccllain 203 

cinnabar  in 44 

Asperites  151,453 

at  Clear  Lake ...221,212,243 

at  Mt.  Shasta 150 

at  San  Luis  Obispo 381 

at  Steamboat  Springs  335 

distribution  of  the 221 

Aucellct,  ago  of 190,201,220 

at  Knoxville... 272 

at  Oathill  335 

characteristics  of 226 

distribution  of 201,203,227,400 

figures  of 230 

first  discovery  of,  iu  California 178 

in  Alaska 201 

iu  Colusa  County 235,367 

iu  Sau  Luis  Obispo  County 381 

iu  Solano  County 378 

in  Spitzbergen 208 

in  Washington  Territory 201 

localities  183,198 

near  Pope  Valley,  Napa  County 369 

not  yet  known  in  Cascade  Kange 200 

occurrence  near  New  Almaden  310 

remarks  of  C.  A.  White  on  226 

speciesof.. 228 

A  ugite,  development  of,  iu  metamorphic  rocks 88 

occurrence  of,  in  metamorphic  rocks 74 

Aurora  mine,  New  I'lria  district 309 

Australia,  cinnabar  in    48 

Austria,  cinnabar  in 38 

Arala,  Mt.in  Servia.  cinnabar  at 41,317 

15. 

Babbage,  C.,  cited 167 

Babiuski,  A.,  cited 21 

Baker  mine,  Lake  County 368 

Ball,  V.,  cited 44 

Ball  structure  iu  basalt 256 

Barba,  L.  S..  cited 23 

I'.an-i-lona  silver  mine,  Nevada,  contains  cinnabar 385 

Kiiifoed,  C.  T.,citid 420,429 

Barite.  in  Oathill  mines 469 

oci  urrence  of,  with  cinnabar 386,388,469 

pseinlomorphs  of  cinnabar  after 397 

Barraude,  .!.,  cited  28 

r.asall.a-B  of 223 

at  Clear  Lake. 245 

477 


478 


INDEX. 


Basalt,  at  Knoxville 280 

at  Kuoxville,  analysis  of 159 

atOathill 355 

at  Steamboat  Springs 337 

at  Sulphur  Bank 252 

at  Sulphur  Bank,  decomposition  of 256 

at  Great  Western  mini- 359 

distribution  and  character  of 150 

glass,  origin  of 161 

glass  at  Sulphur  Bank,  analysis  of 158,159 

glass  from  the  Rossberg 160 

near  New  Idria 300 

occurrence  of,  with  cinnabar 373 

of  Mayacmas  district 376 

Bastite  in  metamorphic  rocks 114 

Baur,  J.  A.,  cited 3 

Beaumont,  15.  de,  cited 172 

Bcckc,  F.,  cited 109,115 

Beleninitei  in  the  Coast  Hauges 196 

Bella  Union  mine,  Napa  County 377 

Berualdez  y  Figueroa,  cited 28 

Biotite  in  metamorphic  rocks  74 

Bischof,  G.,  cited 120,124,433,438 

Bitumen,  at  Knoxville 286 

at  Sulphur  Bank 257 

at  the  Great  Western  mine 360 

at  the  Manzanita  mine 307 

in  Miocene  schists 218 

new  species  of,  io  the  Phoeni  x  mine 372 

Black,  J.,  cited 27 

Blake,  W.  P.,  cited  170,215,315,385 

Blue  Mountains 206 

Blum,  J.K.,  cited 337 

Bohemia,  cinnabar  in 40 

Bolivia,  cinnabar  in  : 23 

Borax,  at  Knoxville 281 

at  Steamboat. ...   A 346 

at  Sulphur  Bank 259 

effect  of,  on  solutions  of  cinnabar 4'il 

orig-n  of ' 440 

Borax  Lake,  described  (see,  alto,  Little  Borax  Lake).. 261, 404 

maggotsin ...  268 

origin  of  borax  in  2(»ii 

water,  analysis  of 205 

Borneo,  cinnabar  in 48 

Bosquet,  cited 23 

Brazil,  cinnabar  in  23 

Breislack,  S. ,  cited  35 

Brcithanpt,  A.,  cited 118 

Brewer,  W.  II.,  cited 176 

British  Columbia,  amalgam  in 384 

Amelia  in 201 

cinnabar  in 384 

Broadhead,  G.  C.,  cited  24 

Brunner,  C.,  cited  420,430 

Buch,  L.  von,  cited    117 

Buckeye  Mine,  Colusa  County 368 

Bugdoll,  cited  211,21 

Bnnseu,  E  ,  cited 26,312,439 

Burat,  A.,  cited  32,33 

Burton,  R.  F.,  cited 24 


Cache  Lake,  conglomerates  of 152 

descri  bed 219, 238 

oiiginof 222 


Page. 

Calderon.S.,  cited 28 

California,  discovery  of  quicksilver  in 8 

( '.ili  torn  ia  coast,  recent  elevation  of 207 

California  mino,  Knoxville  district 281, 283 

California  mines,  geographical  distribution  of 13 

quicksilver  product  in  10 

Callias  of  Athens  ...   28 

Cantua  Creek,  nonconformity  at  190,297 

Cap-chambers > 412 

Carbonates,  conversion  of  rocks  to 392 

effect  of,  on  solutions  of  cinnabar 431 

Carboniferous  formation  in  California  177 

Carboniferous  fossils  in  the  gold  belt 135 

Carboniferous  metamorphic  rocks  208 

Caron,  cited 28 

Cascade  Range 205,  365 

Castillcro,  A.,  cited  8,9 

Castillo,  A.  del,  cited  16,17,18 

Castro,  L.,  cited    16 

Cathrein,  A.,  cited 82 

Caulinitesa.1  Salphur  B.mk 254 

•  Cerro  Bonito  mine,  Fresno  County 380 

Cerro  Gordo  mine,  Fresno  County 380 

Ceylon,  cinnabar  in  47 

Chaboya,  L.,  cited  8 

Cha'.cedonite 390 

Chalcedony  at  Steamboat  Springs —      341 

(See.  also.  Opal.) 

Chalk  Mountain,  andesitc  of    152,  238 

Chambered  veins 410,472 

Champlin,  J.  D.,  cited 10 

Chanconrtois,  fi.  de,  cited  30,52 

Chateliot,  M.  du,  cited 21 

Chiro  licils  at  New  Idria. 294 

Chicogroup 179 

Chico  strata  fn  On  gon  206 

Chico-Teji»n  series,  described 214 

at  Clear  Lake 237 

Chili,  cinnabar  iu  23 

China,  cinnabar  in    46 

Chlorides,  eifect  of,  on  solutions  of  cinnabar 431 

Chlorites  in  metamorphic  rocks 85 

.  Christy,  S.  B.,  cited 4J1.436 

,  Chromic  iron,  at  Knoxville  278 

at  New  Idria 294 

in  serpentine 116 

Chrysolite,  occurrence  of 114 

Cincinnati  mine,  Lake  County 376 

Ciintalur,  at  Knox  villi- 281 

at  N'cw  Alinaden  314 

at  New  Idria   301 

at  Sulphur  Bank  257 

:,t  Steamboat  Springs 350 

conclusions  as  to  foreign  occurrences  of 50 

crystals  of 390 

era  of  deposition 417 

in  basalt 257,282,337,373 

in  granite 350 

iu  nii'tjiunrpliic  rocks,  passim  et 391 

in  sedi ntary  rocks 301,382,391 

known  to  the  ancient  Pel  uviaus 8 

natural  solutions  and  precipitations  of 4:i:> 

occurrence  of,  in  andesite 264,370,379 

oiigmof.  . 55,438,445 

possible  son  l re.s  c.t'    442 

precipitation  of.  ill  Sulphur  Bank 261 


INDEX. 


479 


Page.  Pago. 

Cinni-bar,  relations  to  rocks 441  j  Cope,  F.,  cited 3.S8 

soluble  in  ;un mnnuit.il  solutions 431,269  Copper  accompanying  cinnabar 257,283,34:1,386 

solution  and  precipitation  of 419,473  Credner,  H.,  cited 439 

supposed  substitution  of,  for  rock 42,399  Crosnier,  L.,  cited 21,23 

veins  of 284,307,414  Cross,  W.,  cited 336 

withbarite 386, 39 T  ;  TTrygtaUinp  mctaiuorpliic  rocks 455 

with  gold 367,383  (s,-e,  also,  Metamorphic  rocks  and  Massive  rocks.) 

with  pyrargyrite 370  Crystalline  rocks  at  Knoxville,  ago  of 274 

with  silver not  eruptive 273 

withstibnite 282, 367,  380.  :.s!i  not  precipitates: > 274 

(See,  also,  Ore  deposits.)  Cuuric  sulphide,  solubility  of . 433 

Cinnabar  City,  El  Dorado  County, deposit  at 384  ;  Curtis,  J.  S.,  cited...  398 

Cinnabar  deposits,  age  of  rocks  inclosing 50,416  Cora  Blauca  mine,  New  Almaclen  district .319,324 

at  Abnarten 28,399  Corea>  cinnabar  in  47 

at  Huancavilica 21  Corsica,  cinnabar  in 33 

atldria 38,290  Cortazar,  1).  de,  cited 16,28,49,375 

at  Monte  Amiata 35,290  !  Cotta|  B.  TOn,  citod 36,41,305,357 

atVallalta 34  Courtney,  \V.  S.,  cited 16 

character  of  inclosing  rocks 50,391 

form  and  classification  of 53,416  D. 

from  solutions 55,435  Dull,  \V.U.,  cited  384 

in  Alaska 381  Dana.  E.  S.,  cited 267 

in  Arizona 386  Dana,  J.  D.,  cited 15,77,108,113,118,124,129,166,216,237 

in  British  Columbia 384  Darwin,  G.  H.,  cited 107 

in  California 305  Daubree,  G.  A.,  cited 61, 107,136,172,182,306 

in  Idaho 385  Davidson,  G.,  cited 207 

in  Nevada 385  Dawson,  G.  M.,  cited  381 

in  New  Mexico 386  Day,  T.  D.,  cited 380 

in  Oregon 366  Dead  Broke  mine,  Lake  County 376 

in  Utah 386  ]  Debray,  H.,  cited  421 

minerals  found  with 52  :  Dcchen,  II.  von,  cited 36 

minor,  of  the  Pacific  Slope 470  !  Decomposition,  concentric  255 

of  Africa 43  ;  Delesse,  A.,  cited , 119 

of  Asia 44  Del  Norte  County,  cinnabar  in 366 

of  Australasia 48  Deposits  of  cinnabar,  similarity  of 401 

of  Europe 27  Derby,  O.,  cited 24 

oflceland 24  Des  Cloizranx,  A.,  cited 24 

of  North  America  15  i  Deville,  H.  Ste.-C.,  cited 421 

of  South  America 19  Dewalque,  G.,  cited 28 

relations  of,  to  lines  of  disturbance 51  Diabase,  at  Steamboat  Springs 145 

relations  of,  to  volcanic  phenomena 52  at  Virginia  City 145 

Clarke,  W.B.,  cited 48  !          tufa  on  the  gold  belt 383 

Clayton,  J.  E.,  cited , 386  Diallage  in  metamoiphic  rocks 75 

ClearLako 247  Dicksou,  J.  F.,  citod 47- 

district 461   ]  Dilution,  cllcct  of,  ot>  cinnabar  solutions 429 

fauna  of 220  |  Diorito  in  the  Coast  Ranges 141 

originof 222  '  Doelter,  C.,  cited 394 

region,  descriptive  geology  of 233  ;  Dolomieu.D.,  cited 35,52 

Cloverdale  mine,  Sonoma  County 372  Dolomite,  at  Xcw  Almaden 315 

Coast  Ranges,  andosites  of  the 157  pscudomorphs  of  cinnabar  after :;n7 

dioriteoftlie 144  Doroschin,  P.,  cited 2ni> 

granite  of  the 144  Drasche,  R.  von,  cited 109, 115 

history  of  the 211  Durand,  E.  F. ,  cited 285,286,31)7 

structural  relations  of  the,  to  other  ranges 208,211 

Colusa  County,  cinnabar  in  367  ''•• 

Conistock  Lode,  andejitcs  of  the 336  Earth,  rigidity  of  I  he 168 

compared  with  Steamboat 331,352,448  viscosity  of  the 107 

criticism  of  theory  of  the  geology  of  the .note,  448  Ecuador,  cinnabar  in 20 

diabase  of  the 144  Egleaton,  T.,  cited '. 377,433 

origin  of  ore  in  the 448  Eichstiiilt,  F.,  citod ion,  113, 115 

Concretions 4-,4  Eiclivrald,  E.,  cited 202,204,237 

inChicobeds. 214  '  Elephant  vein,  Napa  County • :(70 

in  sandstone  at  New  Idiia 64,294,300  Elliot,  G.  H.,  cited ],.,! 

theory  of  formation  of 6j  Ennnons,  S.  F.,  cited !,'»,  176,352,306,385,39s 

Condon,  T.,  citod 202,232  Enricpiita  mine,  New  Almaden  district 325 

Conrad,  T.  A.,  cited  42,215  Eon  no  age  of  Tojon  beds  217 


480 


INDEX. 


Page. 

Eocene  at  New  Idria. 2'J9 

Ephydra,  larvae  of,  in  Borax  Lake 268 

Epidote  iu  metamorphic  rocks 86 

Equilibrium,  hydrostatic,  of  the  earth 167 

Erosion,  bearing  of,  on  origin  of  massive  rocks 109 

Errington,  Miss,  cited  200,178 

Eruptions,  traditions  of,  at  Clear  Lake 247 

Eruptive  rocks,  Pre-Tertiary 222,  274 

not  mingled  with  metamorphica 131 

(See,  alto.  Massive  rocks.) 

Eschwege,  W.  L.  von,  cited 24 

Eureka  mine,  Oathill 356 

Europe,  cinnabar  deposits  iu 27 

Everett,  A.H.,  cited 48 

F. 

Farallone  Islands,  granite  of 140 

terraces  of 207 

Feldspars,  conveision  of,  to  serpentine 122 

in  metamorpbic  rocks. 82 

specific  gravity  of 14:! 

Fischbach,  W.,  cited 42,44 

Fischer,  P.,  cited 202 

Fischerde  Waldheim.G.,  cited 227 

Fissure  system,  at  New  Almaden  317,  321 

at  various  mines 414 

Fissures,  discussion  of 407 

formation  of,  under  great  pressure 414 

Flagstaff  mine,  Lake  County 376 

Floyd,  R.  S.,  cited 250 

Foreign  occurrences  of  cinnabar 14,  432 

Formations,  found  iu  California 1~7 

of  California,  classified  by  Whitney  and  Gabb 179 

Fossils,  Chico,  at  New  Idria 291 

of  Cache  Lake  Pliocene 220 

of  the  Wallala  beds 214 

Tejon 215 

Tertiary,  at  New  Almaden  312 

Fouqu6  and  MicheLLevy 86, 109. 114, 115, 129,421 

France,  cinnabar  in - 32 

Francke,  H.,  cited - 86 

Fraser  River,  cinnabar  and  gold  uear 384 

Fugger  Brothers  controlled  Almaden 28 

Furnace,  tirst  continuous  quicksilver 309 

G. 

Gabb,  W.  M.,  cited  . .  .16, 176, 178, 179, 184, 196, 198,  205, 207, 215 

228,  231,  237,  310 

Gabbro,  metamorpbic 101 

olivinitic,  at  Now  Almaden 312 

Gahn,J.G.,  cited «3 

Galena,  insolubility  of 434 

Gangne  minerals,  at  Knoxville 279,285 

at  New  Almaden 314 

at  Sulphur  Bank 257 

in  cinnabar  deposits •  • — 388,472 

Gaugzng 410 

Gannett,  H.,  cited  163 

Garces,  E.,  discovered  Huancavelica "1 

Garnet  in  metaniorphic  rocks - 87 

Gases,  at  Xe\v  Iilria '•      308 

at  Phomix  mine,  analysis  of 373 

at  Steamboat  Springs 342 

at  Sulphur  Biink,  analysis  of 238 

soll.itari. ,  at  Knoxville 287 

(fault,  IIorsHowti  l>  ill  referred  to  the 20~> 


Page. 

Uavilau  Kange,  limestone  of  the ....  181 

rocks  of  the l.'H 

Geikie,  A.,  cited : 256 

Genesee  Valley,  fossils  in  195 

Genesis  of  cinnabar 401 

at  Pope  Valley 374 

Geology,  importance  of,  to  mining  418 

of  the  quicksilver  belt 176,460 

Germany,  cinnabar  in  36 

Geysers,  the 377 

Gibhs,  W.,  cited  % 53 

Gilbert,  G.  K.,  cited 209 

Glaucopbanc,  in  metamorphic  rooks 76 

Glaucophane-schist 102 

analysis  of 101 

at  Wall  Street  mine 375 

Gmelin-Kraut,  cited 430 

Godfrey,  J.  G.  H 47 

Gold,  extracted  from  quaitz  by  pressure 198 

genesis  of  dcposi  ts  of 4  30 

product  compared  with  that  of  quicksilver. 3 

solubility  of 433 

Gold  accompanying  cinuabar,  at  Baker  mine 3C8 

at  Knoxville 381! 

at  Manzanita  mine 307 

at  Pica^ho  mine 309 

at  Steamboat  Springs 344 

at  Sulphur  Bank 257 

Gold  belt  defined 195 

Gomes, -I.  C.,  cited 24 

Goodyear,  W.  A.,  cited 207, 28.',  283, 309,  315,  368, 379 

Gottschc,  C.,  cited 47 

Gower,  cited 47 

Granite,  age  of  the 141 

at  New  Almaden 311 

distribution  of  140,180 

intrusive  141 

of  California  in  part  primeval  174 

of  Lower  California 207 

porphyry 143 

relations  of,  to  other  rocks 1 70 

the  probable  source  of  quicksilver 446 

underlying  the  Coast  Ranges 60 

Granite  at  Steamboat  Springs 332 

metals  in  350 

Grate  structure,  in  opal 393 

in  serpentine 115 

Great  Eastern  district,  geology  of 302,469 

Grt at  Eastern  mine,  Lake  County 375 

Great  Eastern  mine,  Sonoma  County ?62 

Great  Geyser,  Iceland 24 

Great  valley  of  California,  elevation  of 200 

Great  Western  district,  geology  of 358,469 

Greenland,  Amelia  in 201, 203 

Groddeck,  A.  von.  cited 41,317,400 

Guadalcazar,  Mexico,  cinnabar  at 17 

Guadalupfmiue 326 

Gualala,  Mendocino  County,  fossils  near 213 

Gnancavelica.     (Ore  llmm-m  lica.) 

Guatemala,  cinnabar  in 19 

Guillemin-Tarayre.  E.,  cited 31 

Giimbcl,  C.  W.,  cited 151 


II. 

Hague,  J.  D.,  cited 

lla^u    and  Iddinss.  cited  


27 

145,  MB,  147,  157 


INDEX. 


481 


I'";;''.  J. 

Hull,  J..  cited 210  .  Page. 

Hall,  T.J.,  cited 283     Jameson,  B.,  cited 27 

Hanks,  H.  G.,  cited 76,  113,  3d4      Jauin,  L.,  cited. xiv,325, 327, 375,  380, 382, 385 

Haushofer,  K.,  cited 112  !  Japan,  ciuuabar  in 47 

Hnutefeuille,  I1.,  cited  : 15      'lava,  cinnabar  in .48 

Hatty,  R.  J.,  cited 100      Johnston,  K.,  cited 03 

Hawkins,  R.  K.,  cited 19      Josephine  mine,  San  Luis  Obiapo  County 382 

H.-at  of  thermal  springs,  origin  of 411      Julicn,  A.  A.,  cited 66 

Heckmanne,  A.,  cited 31,43      Jurassic  fossils  in  Goneseo  Valley 195 

Hector,  J.,  cited 50,  340      Jura-Trias  at  Steamboat  Springs _.  128, 333 

Heilprin,  A.,  cited 216 

Helmhacker,  R ,  cited ; 28 

Hilgard,  E.  W.,  cited 4      Kamtschatka,  cinnabar  in 45 

Hiriakoff,  M.,  cited 43      Keller,  cited 21 

Historical  geology 170,460  '   Kemble,  G.  W.,  cited 3gj 

History  and  statistics  of  quicksilver 1,451      Kennan,  G.,  cited 45 

Hoffmann,  F.,  cited 35      Kentucky  mine,  Sonoma  County 377 

Hoffmann,  F.  C.,  cited 235,  370      Koyserling,  A,,  cited 202,  201,  227  231 

Hoffmann,.!.  I).,  c  itul 233,298      Keystone  mine,  San  Luis  Obispo  County 382 

Hollands,  I).,  cited 3:1      Kicking  Horse  Pass,  cinnabar  at 394 

Hol/.apfe',  E  .  cited 231      Kimball,  J.  P.,  cited 3 

Homatlico  Kivor,  cinnabar  noar  384   ,  King,  Clarence,  cited 170,178,201,200,210,219,267 

Hornblende,  in  metamorpliic  rocks 75  •   Kirchhoff,  G.  S.  C.,  cited  420 

metasomatic  development  of 89      Klemm,  J.G.,  cited 97 

Hornblende-mica-andesite 147      Knoxville  beds,  at  New  Idria 2D2 

Horsetown  beds,  defined 180  at  Knoxville 271 

fauna  of COii  at  Sulphnr  Bank  251 

non-conformity  beneath  tlio 205  at  Clear  Lake 235 

referred  to  the  Gault 205  Aurrlla  In 230 

straligraphical  ivlations  oj    UH  defined 1^0 

Hut  springs,  association  of,  with  mines 381,382,402   :          fauna  of 11)8 

wuirccof  heat  of 411   •  Knoxville  district,  descriptive  geology  of 271,401 

::»».  H.,  cited 16      Knoxvillite,  new  mineral 27D 

Huancaveliea.  Peru 4,C,2t      Kokscharow,  N.  von,  cited 44 

Huitzuco,  Mexico,  cinnabar  at 18  .  Kolbe,  H.,  cited 430 

Hun'bolclt,  A.  von,  cited 16, 17,  19,20,22,54, 172      Koiiocti,  Mount ! 233 

Hamic  acid,  concretions  due  to 67      Krantz,  A.  {?),  cited 393 

Hungary,  cinnabar  in. 41      Kriimmel,  O.,  cited 170 

Hunt,  T.S., cited 82,117,119,120,130,172,343   !   Kuss,  H.,  cited 6,28,32,42 

Ilussak.  E.,  cited 10^,  113      Kwei-Chau,  China,  cinnabar  in  4,6,46 

Hut  ton,  Captain,  cited 44 

Hntton,  F.  W.,  cited 49 

Hydrocarbons,  absent  at  Steamboat  Springs...                  342  r 

Lagorio,  A.,  cited  . 

absent  in  many  volcanic  emanations i-;o 

Laguereuno,  T.L.,  cited...  10 

Hypersthene  m  basalt  157  

Hvposulphites,  formation  of 430        ''t       '^««>.  ^1>«  near 383 

at  Steamboat  Springs 8»8      Lak7"»«.Knoxv,lIe  district 282 

at  Sulphur  Bank..  0      Lilns<1f  •  H"  "^ 45 

Lateral  secretion  theory 352,442 

Later  hornblende  amlcsite 

Ice,  behavior  of,  in  melting  70      Laiir,  P., cited 33, 

Iceland,  cinnabar  in 24  Laras 

Idaho,  cinnabar  in 285  age  and  distribution  of  the •.•.] 

Idilings.    See  Hague  and  ladings.  of  California  not  fused  sediments '.".'.'.'.  174 

Idria  mine,  Austria 4,5,7,38   ,   Lead  sulphide,  insolubility  of 

Ildekansk  mine,  Siberia 44      Leavens,  II.  W.,  cited .";";  36G 

Illuminationoftuunelbyheliost.it  308      Le  Conte,  J.,  cited .206, 209' 257  263 

Ilmenitein  metamorpliic  rocks 34      Lecso,  J.  P.,  cited  

Impregnation!  of  cinnabar 5J,  4;o      Lehmanu,  J.,  cited, 13o 

India,  British,  cinnalur  in    47      Leipoldt,  G., cited .^..........        169 

India,  Dutch,  cinuabir  in    48       L,s,,uc.  TUX,  L.,  cited  .'.".".'      25i 

India,  Spanish,  cinnahai •  in 4g   !   Lidell  hot  springs 371 

Injection  theory  of  ore  deposition  442  \  Limestone,  of  Gavilan  Range  igi 

Inoceramus,  occurrence  of 181  of  Neocomian  age CO 

Inntcramus  Piochii 1%,  1:17  of  Now  Almadon 31 1 

Italy,  cinnabar  in 33      Lindgi  en,  W.,  cited ......xiv,  119,273330 

Ivanhoe  claim,  Oathill ::,i^      Lindstrom,  G.,  cited 203?227 

MON   XIII 31 


482 


INDEX. 


Page. 

Linked  veins 409 

Lipolil,  M.  V.,  cited 5,38,42,54,398,400 

Little  Borax  Lake 241  238 

Little  Missouri  mine,  Souoma  County 377 

Little  Paaocho  mine,  Fresno  County 381) 

Little  Sulphur  Bank 264 

Livermore  mine,  Sonoma  County 377 

Liversidge,  A.,  cited 50 

Los  Prietos  mine,  Santa  Barbara  County 382 

Lotti,  B.,  cited  35,118 

Lower  California,  character  of 207 

Wallala  beds  in 213 

Luckliardt,  C.  A. .cited 307,374,377 

Lucky  Boy  claim,  Piuto  County,  Utah 385 

Liidecke,  0.,  cited 77 

Lycll,  C.,  cited 217 

M. 

MacCulloch,  J.,citcd 172 

Maggots  in  Borax  Lake 268 

Mallet,  E.,  cited 172 

Manhattan  mine,  Kuoxvillc  district 282 

Manzanita  mine,  Colusa  County 307 

Marcasite,  solubility  in  sodium  sulpbiuo 432 

Marcou.J.,  cited 176,187,193,198,216,218 

Mariposa  beds 180 

Amelia  in 230 

auriferous 198 

determined  as  Cretaceous 204 

determined  as  Jurassic 196 

determined  as  Triassio 198 

fauna  of 11.8 

identical  with  Kuoxvillc  beds 195,197 

Mariposa  estate,  fossils  on  the 178 

Marmolite i 114 

Marsh,  O.  C.,  cited 221 

Martinez  group 179,180 

Massive  rocks 140.459 

origin  of  the 164,168 

primeval 171 

texture  of 162 

Mast.C.L.,  cited 383 

Maxwell,  J.W.C.,  cited 302,308,383,390 

Mayacmas  district,  geology  of  the 368 

Medina,  B.  de,  invented  amalgamation  process 28 

Meek.  F.I!.,  cited  178,190,232 

Mthu,  M.C.,  cited 421 

Melville,  W.  II.,  cited  xiii,  360,  372, 430 

Meudelojeff,  C.,  cited 171 

Mercuric  sulphide,  solution  anil  preparation  of  ..26!),  419,435 
(See,  also,  Cinnabar.) 

Mercury,  sulphosalts  of 422,  425,  4.'6,  429 

Mercury  and   Manzanita   veins,   Napa  Consolidated 

mine 350,415 

Metacinnabarite,  at  Baker  mine 28^,308 

atKnoxvillo 284 

atNewIdria 302 

formation  of 436 

in  Mexico  19 

in  New  Zealand  49 

in  the  Bavarian  Palatinate 37 

Metals  in  tin;  Stra]nl">;it  Springs  deposit 313 

Metamorphic  pebbles  in  Chico  and  Miorene  b::ds. .   18f>,  190. 

2!)5 

Metauiorph  ic  rocks 56,  4.~>5 

ngeofthe 57,183,188 


Page. 
Metamorphic  rocks,  at  Great  Eastern  mine  ............      362 

at  Great  "Western  mine  ............................      358 

at  Knoxville,  age  of  ..............................  272,274 

at  Xew  Almadcn  .............  .  ...............  _____      319 

atNcwIdria  .....................................      393 

at  Oathill  .........................................      355 

at  Steamb  jat  ..........................  :  ..........  128,  333 

at  Sulphur  Bank  .................................      251 

Carboniferous  ....................................      208 

compared  with  the  Archojan  ......................      138 

ci'i  stalline,  classified  .............................        72 

decomposition  ofthe  ..............................      105 

granular  ........................................  ..        93 

minerals  formed  in  ................................        74 

of  Gavilan  Range  .................................      1-8 

of  Neocomian  age  .........................  .......       60 

eerpentinizatiou  of  ...............................      121 

(See,  also,  Neocomian  and  Serpentine.) 
Metamorphism,  chemical  character  of  ...............      134 

conditions  attending  ..........  ..  ..................      129 

dynamic  conditions  of  ............................      133 

eras  of  ....................................  57,131,187,210 

influence  of,  on  erosion  ............................      23G 

in  the  Coast  Kanges  ...............................      181 

of  eruptive  ro=ks  .................................        59 

Pre-Cretaccous  ...........  .......................      2C8 

pressure  attending  .............................  ...      132 

proofs  of  ..........................................      129 

theories  of  ........................................        58 

Metasomatism  ........................................  57,453 

Mctastibnito  ........   ................................  343,383 

Mexico,  cinnabar  in  ..................................        16 

Michel-Levy,  A.,  cited  ................................        76 

(See,  also,  Fouqne  and  Michel-  Levy.) 
Middendoiff,  A.  T.  von,  cited  ........................  203,227 

Milierite,  at  Knoxville  ...............................      286 

in  the  Pko>uix  mino.  ____  .  ............  .  ........  ....      372 

Miucnkoff,  cited  .......  ..............................        43 

Minerals,  converted  to  serpentine  .........  .  ...........      122 

found  in  metamorphic  rocks  ...................  ....        74 

resulting  from  metasomatism  .....................      455 

Mines,  various,  comparison  between  ..................      401 

Miocene,  at  New  Almadcn  ...........................      312 

conformable  with  the  Tejon  .......................      19i 

discussed  .......................................  218,  461 

metamorphosed  near  San  Jose  ...................  185,  180 

uucouformable  with  the  Tejon  ......  .  .............      193 

uncouformablo  with  the  Ncocomian  .............  :      192 

Mispickcl  at  \c\v  Almadcn  ..........................      315 

Moesta,  F.  A.,  cited  ............   .....................        17 

Mohelhel,  Ibn,  cited  ..................................        44 

Molasse  compared  with  California  rocks  ..............      187 

Moncasterio,  J.  de,  cited  .............................  28,42 

Monte  Amiata,  Tuscany,  ul;issy  trachyte  of  ..........       159 

Moore,  G.  E.,  cited   ...............................  37,49,283 

Mt.  Diablo,  andesito  at  ......  .....  ..................       155 

cinnabar  at  .........................................       373 

Mt.  Jackson  mine,  Great  Eastern  district  ............  362,304 

Mt.  Shasta,  aspwritps  of  ...............................       336 

Munroe,  11.  S.,  cited    ..  .............................        47 

Muscovite  in  mrtamorphic  roeks.  .....................        74 


N. 


Na;i:i  Consolidated  mines 
Xapaliti-.  a  m-w  bitumen 
Xativo  ipiicksilver.  at  Pi-ii 


334,  356 
372 
376 


INDEX. 


483 


Page.  !                                                                                                Page. 

Native  quicksilver,  at  Rattlesnake  mine 377      Ore  deposition,  theories  of 442 

at  Wall  Street  mine 375  Ore  deposits,  age  of  .. 

mode  of  occurrence 3P8  at  Groat  E.isteni  mine    30:1 

precipitation  of 4:!°  '          at  Great  Western  mine 3.~>9 

Neocomian,  at  Knoxvillo 271  at  Knoxrille 281 

at  O.vthill :; '•'  at  ManMinita  mine 307 

in  Jt'ayacroas  district a09  at  New  Alraaaon 314,310,323,327 

in  Solano  County 378  at  New  Idria  301 

strata , 193,400  at  Steamboat 342 

(See,  also,  Meta-norphic  rocks  and  AttceUx.)  at  Sulphur  Bank.. 257.203 

Nertschinsk  district,  Siberia,  cinnabar  in 45  character  of 410 

Net  structure  115.401  discnssicii  of 387,471 

New  Al.Na.'.eiidistrict.u.-i'logy  "'' ....3IO,4ii7  form  of     40:, 

lissare  system  of -3-8  minerals  in 387 

XY» •  Almadfii  mil,,..  .llKOVeryof minor,  descriptions  of 305,470 

plans  ami  sections  of 318  j          origin  of   438 

Newberrv,  J.  S  ,  cited 170,  448,  nu(«  relations  of,  to  general  geology 2.'5 

New  Idria.,  Cliico-T.'jon  scries  at 215  wall  rocks  of 391 

distiict,  geology  of 201,105      Oregon,  Chico  beds  in  200 

mine 301  ;          cinnabar  in 360 

non-conformity  at  l«>      Organic  matter,  concretions  duo  to 60 

s.,nd-tono  concretion  from  ^      Oscrskij,  A.,  cited 45 

New  Idiian  mine,  Douglas  County,  Oregon 360 

New  Zealand,  cinnabar  in 49 

Nicholas,  W.,  cited «      Panoche  district 379 

Nichols  R.K.   cited 233      Panoche  Grande  mine,  Fresno  County 380 

Xo,liil,.»and  pebbles   theory  of  formation  of 68,455      Paso  Roblca  hot  springs 381 

Xoggeratli.  A.,  eited '....15,19,23,27,28,32,33,35,45,49      Pavlow,  A.,  cited 204,229 

Non-conformity,  between  the  Tejon  and  Miocene 218  i  Pebbles,  formation  of 71 

Post-Mioccno  ...  218,461      Ponce's  Ranch,  Carboniferous  fossils  at 195 

Non-conformity,  Posi-Ncocomian 177,188,460      Perez-Eosales,  V.,  cited 23 

atNewAlmadcn 313      Perowskito  in  opal 394 

atNew  Idria 295      Peru,  cinnabar  in   20 

indirect  evidence  of 192  ,   Pctersen,  T.,  cited 160 

on  the  Gold  Belt 196      Pniicker,  L.,  cited 21 

paleontologicnl  evidence  of 193  !  Philippine  Islands,  cinnabar  in 48 

Novak,, I,  cited 7       Phillips,  J.  A.,  cited 3,23,352 

Nova  Scotia,  cinnabar  in 16      Pl'ff nix  mine,  Napa  County 371 

Pluemx  Xo.  2  mine.  Napa  County .      374 

1'kolas  borings  207 

I'hthanite 105 

Oakland  miuo,  Sonoma  County 377      Phylloxera,  quicksilver  us.d  to  kill 3 

Oakvillc  mine,  Napa  County 377      Picaoho  mine,  San  Benito  County 309 

Oathill  district,  geology  of 354,409      Pinart,  A.  L.,  cited 202 

Obsidian,  andesilic    153,242      Pioneer  mine,  Lake  County 376 

basaltic 158,252  ;    pipo  veins 411 

Oceanic  mine,  San  Luis  Obispo  County 382  !   Pittsburgh  mine,  Lake  County 378 

Ocean  View  mine,  San  Luis  Ohispo  County 3S2  !,  Pliny,  eited 4,28 

OH  vine  in  andesito  153      Pliocene 219, 238 

Onofrite  at  Kuoxville 285  probable  at  Now  Almaden 314 

Opal  S90,  392      Point  Reyes,  cinnabar  at. 379 

at  Great  Eastern  mine,  Lake  County 375      Polar  Star  mine,  San  Luis  Obispo  County 382 

at  Great  Eastern  mine,  Sonoma  County 363      Pope  mine,  Napa  County 374 

at  Great  Western  mine 360      Portugal,  cinnabar  in  27 

at  Knoxville L81, 286      Posepnyta  at  Great  Western,  analysis  of 360 

at  New  Almaden 327      Post-Pliocene  described 219 

at  Steamboat  Springs 341      Potassic  sulphide,  action  of,  on  cinnabar 4!9 

Oppcrt,  E.,  cited  47      Potassic  sulphydrate,  action  of,  on  cinnabar 419 

Orbigny,  A.D.d'.cited 204      Prado,  C.  de,  cited 18,42,397,399 

Orcutt,  C.  K.,  cited 213      Primeval  rocks 171 

Ore,  description  of 387  !  Pseudodiabase 94 

microscopical  character  of , 389  analysis  of 98,99 

origin  of : 438,475      Pscudodiorite 94,99 

(See.  also,  Cinnabar.)  analysis  of 101 

Ore  deposition,  at  Steamboat  Springs 346      Pseudomorphism  and  substitution 396 

at  Sulphur  liank 269       Paeinbimorph  .  einnaKi:  after  h.vilc 397 


484 


INDEX. 


1 
365 

9 
245 


Page. 

Pseudomorphs,  ciuuabar  after  magncsite  .....  .........      397 

galena  after  calcito  ...............................      398 

Pumpelly,  R.,  cited  .................................  46,  47,  51 

Pyrargyrite  with  cinnabar  ...........................      370 

Pyrite,  solubility  of  ...................................      432 

Q. 
Quartz,  conversion  of,  to  serpentine  ..................      123 

Quicksilver,  average  price  of 

belt 

C'astillero's  test  for 

deposits  in  andcsite 

discovery  in  California 

historical  notes  on.  ..........................  « 

in  Scandinavia 

in  Scotland  ...............  ,  ...... 

in  Steamboat  Springs  water 

mines  of  California,  distribution  of  ............ 

mining,  future  of 

native,  formation  of  .................  .  ........  .'. 

foreign  occurrences  of  ........................... 

often  found  with  gold  and  silver  .................. 

ores,  conclusions  as  to  occurrence  of  ..............  50, 

product  at  Steamboat  ............................. 

product  in  California  .............................. 

product  in  Hungary  ............................... 

product  in  Tuscany  .............................. 

products  of  districts  compared  ................... 

relative  abundance  of,  in  nature  .................. 

relative  value  of  .................................. 

rock  (see,  also,  Opal)  .............................. 

statistics  ..............................  ___  ........ 

uses  of  ....................................  .  ....... 

value  of  product  of,  since  1850  ..................... 

world's  product  of,  since  1850  ...................  .  . 


27 

:147 

13 

417 

436 

U 

9 

410 

'.'•">- 

10 

41 

C 

7 

2 

1 

63 
1 
;j 
3 
3 


K. 


Raimondi,  A.,  cited  ...................................        20 

Kamirez,  S,  cited  ...................................  16,17,18 

Rando),  J.  B.,  cited  ..........................  .  .......  3,6,10 

Rath,  Q.  vom,  cited  .........................  20,23,34,118,159 

licude,  F.,  cited  .................................  xiv,  319,321 

Rcdingtonite,  now  mineral  ............................      279 

Red  i  ngton  mine  ......................................  281,  284 

discovery  of  ......................................        10 

Kccd  mine  (  or  California  mine),  Enoxville  district  ...281,283 
Kcnatd,  A.,  cited  .....................................  86,  106 

Results,  brief  outline  of  ...............................     xvii 

Reticnl.ited  veins  of  cinnabar  .........................        54 

Kettss,  A.  E.,  cited  .....................................      398 

Reycr.E.,  cited  .......................................      441 

Rhynchonella,  in  Colusa  County  ......................  '  235 

occurrence  of  .....................................      183 

Riyollle  ..............................................  156 

age  of  .............................................      223 

dike  at  Ne\v  Almaden  ..................  ..........  313,329 

Richthofen,  F.  von,  cited  ..................  6,46,313,853,448 

Rigidity  of  the  earth  ..................................      168 

Kilc.y,  C.  V.,  cited  .....................................      268 

Riuconada  mine,  San  Luis  Obispo  County  .............      381 

Uising,  W.  B.,  cited  ..................................  257,203 

Rivero,  M.  E.  de,  cited  .............................  7,17,21,22 

Roach,  J.,  cited  .......................................      SOS 

Rockland  district,  Del  Norte  County,  cinnabar  iu  ....      366 

Racks,  sedimentary  ...................................  56,  453 

massive.  .........................................  140,  159 


Tag,-. 

Holland,  G.,  cited  36,315 

Kosenbti8c.li,  H.,  cited 86,  109,  118,  390 

Uo-^lMTg.  basalt  from  the  160 

Roth,  J.,  cited  48,66,77,118,422 

Russell,  I.,  cited 267 

Russia,  Aticella  in 202 

(•imiahnrin 43 

Rutile  iu  metaiDorpUlc  rocks 84 

S. 

Sain.nl,  J.  M.,  cited 44 

Sr.  Jolm'.s  mine,  Solano  County  378 

San  Antonio  miue,  New  Almailen  ill  strict 327 

San  Bernardino,  cinnabar  at  383 

San  Cailos  mine,  NVw  Idrin  district  308 

Sandberger,  F.,  cited 18,118,351,436 

Sandstone,  alteration  of  the 63 

alte: •('<!,  development  of  minerals  in 87 

analysis  of 92 

component  in  in,- ra  Is  of t!2 

derived  from  granite  60,61 

interstitial  space  in... 399 

microscopical  character  of 61 

transformation  of.  to  serpentine 121,  277 

weathering  of  the 63 

San  Francisco,  cinnabar  at. 379 

San  Francisquito  Pass,  metamorphic  rocks  of 185 

San  Juan  Bautista  mine,  Santa  Clara  County 379 

San  Matro  mine,  New  Alntaden  district 327 

Santa  Cruz,  terraces  at. 207 

Santo  Domingo,  cinnabar  in  16 

Saussurite  in  mctamorphic  rocks 82 

Scandinavia,  quicksilver  in 27 

Scapolite 129 

Schecrer,  T. ,  cited 119,163,173 

Schindler,  A.  II. .cited  44 

Schmitz,  cited 383 

Schranf,  A.,  cited 87,127,394 

SelitockiiiLrer,  J.  von,  cited 360 

Scotland,  quicksilver  in 27 

Sci-ope,  <!.!'.,  cited  172 

Sedimentary  rocks 5G,;V.),4.i:i 

Scnar'niont,  H.  de,  cited  434 

Serpentine 108,457 

analyses  of - 110.111 

at  Great   \\'e-t:'in  mine 359 

itt  Knoxville 270 

at  Xnw  Almadcti   311 

at  Xewldria 293 

at  Sulphur  Bank 251 

Carboniferous 210 

colloid - 115 

decomposition  of 127 

derived  from  olivine 115 

derived  trout  peridotite 59 

derived  from  sandstone 277 

grate  structure  in 115 

microstructure  of ,  114 

mineralogical  character  of 108 

minerals  yielding 118 

net  structure  in 115 

origin  of 117 

pseudomorphs  of 118 

relations  to  olivine  rocks 312 

Serpcntinization,  course  of 126 

Si  f\  ia.  ei  nn  a  bar  in 41 


INDEX. 


485 


Page. 

Sh:i»ta group 179,  isu 

Siberia,  cinnabar  in 44 

Sierra  Nevada,  persistence  of  the 209 

structural  relations  of  the,  to  other  ranges    '-'os 

Silica  of  sinters  at  Steamboat  Springs 341 

Mlicification.atKnoxville 279 

opaline 392 

Sillem,  cited 398 

Silliman,  B.,  ci»ed 815 

Silver,  abundance  of,  in  nature  relatively  to  quick- 
silver            2 

accompanying  cinnabar 19, 309, 370,  38:>,  :!so 

product  compared  with  that  of  quicksilver 3 

sulphide,  insolubility  of 431 

Silver  Bow  mine,  Napa  County.' 373 

Simnndi,  A 351,419 

Sinters,  absence  of,  explained 405 

dendritic,  at  Borax  Lake 266 

at  Steamboat  Springs 340 

Siaapo,  ancient  name  for  AlmaJen 4 

Skertclily.  S.  B.J.,  cited 48 

Smyth,  11.  B.,  cited  49 

Sodic  hydrate,  influence  of,  on  the  solubility  of  cin- 
nabar         42.' 

Sodic  sulphide,  in  nature 473 

solubility  of  cinnab.ir  in 419,423 

solubility  of  pyrite  in 432 

Sodie  snlpl'ydrate,  behavior  of,  to  cinnabar 419,41>4,428 

Soctboer,  A.,  cited 3 

Solutions  of  cinnabar,  effects  of  dilution  on 429 

eft'ects  of  other  substances  on 431 

Sonuensehein,  F.  L. ,  cited 383 

Sonoma  mine,  Sonoma  County 377 

Soutb  America,  cinnabar  in II 

Southern  California 140 

Spain,  cinnabar  in 27 

Spitsbergen,  Aucetta  in 203 

Springs  at  Steamboat 338 

Star  mine,  Napa  County 373 

Statistics  auil  history  of  quicksilver 1,451 

Stay  ton  mines,  San  Beuito  County 380 

Steamboat  Springs  district,  geology  of 331,463 

diabase  at 144 

granite  of 141 

raetamorpbic  rocks  of 128 

Stearns,  R.  E.  C.,  cited 220,240 

Stein,  W.,  cited 420 

Stotzner,  A.,  cited 23 

Stibnitc 282,367,380,389 

Stoliczka,  !•'.,  cited 227,231 

Ulriitiiiniiiiiat  Borax  Lake 2(i8 

Substitution  of  cinnabar  for  rock  .  288,  315,317,  394,  399 

Sulphides,  associated  with  cinuabar 388 

origin  of 438 

Sulphur,  at  Manzanitamiue 367 

at  Steamboat. ..'. 346 

at  Sulphur  Bank 254,  463 

Sulphur  Bank,  descriptive  geology  of 251 

discovery  of 10 

future  prospects  of 264 

high  temperature  at 259 

resemblance  of,  to  other  deposits  263,402 

Sulphur  Bank  mine 253,263 

Sulphur  deposition,  at  Knoxvllle 287 

at  Sulphur  Bank 254 

Sulphuric  acid  at  Sulphur  Bank,  genesis  of 255 


Page. 

Sulphurous  acitl  at  Sulphur  Bank 255 

Sulphur  springs,  hot.  at  tho  Mauzauita 367 

Sumatra,  cinnabar  in  48 

Summary  of  results 451 

Similrrlandaud  Luckhardt  mine  382 

Suiiol,  A.,  cited 8 

Synclinal  hills  in  metamorphic  rocks 183 

Szabo,  J.,  citod 118 

T. 

Talc  in  metamorphic  rocks 113 

Tejon,  atNewIdiia 299 

beds,  age  of  the 177 

beds  discussed 214 

conformable  with  the  Chico 192 

controversy  as  to  age  of 215 

determined  as  Eocene 217 

group 179,180 

Terraces  of  Californ  ia  coast 207 

Texture  of  massive  rocks 162 

Thenard,  P.,  cited 67 

Thermochemistry,  application  of 427 

newlawof 119 

Thibet,  cinnabar  in  47 

Thinolite 267 

'   Thomsen,  J.,  cited 430 

Thomson,  W.,  cited 167 

Tbuiach,  H.,  cited 84 

TlmistonLake 241 

Ticrnanuite  in  Utah 385 

Tin  product  compared  with  that  of  quicksilver 3 

Tissot,  A.,  cited « 

Titauite  in  metamorphic  rocks...... 85 

Todos  Santos  Bay,  Wallala  beds  at 213 

Tonla,  F.,  cited 203,227 

Trachytes 150,155 

Transition  andesites .  148 

Trask,  J.  B.,  cited 177 

Trautschold,  II.,  cited. 204 

Trinity  County,  cinnabar  in 366 

Trinity  mine 366 

Tri;issi<-  fossils  at  Genesoe  Valley 195 

Ti-iassic  in  California 178,198 

Tschermak.G.,  cited 43,86, 118, 143, 43!) 

Tulo  roots,  silicifled,  at  Sulphur  Bank 254 

TuUborg.S.  A  ,  cited 227,231 

Tunis,  cinnabar  in 44 

Turkey,  cinnabar  in 42 

<  Turner,  II.  W.,  cited xiv,354 

Tuscan  mines,  product  of 6 

Tuscan  Springs,  fiioctramux  at 197 

•  Tuscany,  cinnabar  in 35 

U. 

Uncle  Sam  Mountain  (Konocti)  233 

United  States,  cinnabar  in,  confined  to  Pacific  slope..  15 

Upheaval,  Post-Miocene 218 

I'ost-N'eocomiiui 1!;8 

Upheavals,  exposure  of  primeval  rocks  by 166 

1'ralite  in  metamorphic  rocks 75 

I'tali,  tirmannlte  and  cinnabar  in 385 

V. 

Vallalta,  description  of 34 

principal  mine  in  Venetia ...  5 

Valley  mine,  Napa  County 355,371 


486 


INDEX. 


Page. 

Veatch.J.  A.,  cited 205 

Vegetable  growths  in  springs  at  Steamboat  Springs..  340 

Vein  chambers 412 

Veins,  at  Oathill 350 

discussed 40" 

of  cinnabar 4(16,472 

of  cinnabar  at  Knqxville 288 

of  cinnabar  in  foreign  countries 53 

recent,  at  Steamboat  Springs  340 

Velten  and  Lehmaun,  cited.. 18 

Vcrbeek.  R.D.M.,  cited 48 

Vermilion,  use  of  quicksilver  in  manufacture  of 3 

Verneuil,  P.  E.  P.  do,  cited 28 

Viscosity  of  the  earth.   --•  167 

Volcanic  action  evinced  at  various  mine's 401 

Volcanic  cones,  form  of,  at  Sulphur  Bank 253 

Volcanic  rocks,  rel:it'on  of  deposits  to 417 

W. 

Wadsworth,  M.  E.,  cited 383 

Wagner,  R.,  cited 421 

Wahsatch  range 209 

Wallala,  etymology  of 213 

Wallala  beds,  composition  of 140 

discussed 213 

uncon  form  able  with  Neocomian 191, 191 

Wallala  group 179 

Wall  rocks 391,410 

WallStreet  mine,  Lake  County 375 


Page. 

Walker,  G.  T.,  cited 19 

Washington  mine,  Napa  County 319,324,374 

Washington  Territory,  Amelia  in 201 

Washoe  district,  Nevad:v,  audcsites  of 149 

diabase  of 14."i 

Washoe  rocks,  nodules  in 71 

Water,  of  Borax  Lake  265 

of  Steamboat  Springs 346 

of  Sulphur  Bank 259 

Weber,  K.,  cited 420,  42J 

Webster,  H.  A. .cited 2tf 

Weigaud,  B.,  cited 109 

White.  C.  A.,  cited xiii,  17ti,  198,  'JOt,  209,  213, 333, 460 

Hcuuirks  on  the  genus  Aucrlla  by 226 

Whilcaves.  3.  P.,  cited  202,204,228 

Whitney,  J.  D.,  cited  ...46,121,140,155,176,179,185,192,215, 

218,  224,  242,  265,  313,  376,  383 

Williams,  J.  F.,  cited    180 

Z. 

Zincken  C.,  cited 44 

Zinc  sulphide,  solubility  of 434 

Zircon  in  metamorphic  rocks    87 

2irkcl,  F..  cited "« 

Zittel,K.A.,cited 227,231 

Zoisite, analysis  of 79,80 

an  evidence  of  metainorphism 129 

in  metamorphic  rocks 77 


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